1
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Goettl SJ, Yang Z, He C, Somani A, Portela-Gonzalez A, Sander W, Mebel AM, Kaiser RI. Exploring the chemical dynamics of phenanthrene (C 14H 10) formation via the bimolecular gas-phase reaction of the phenylethynyl radical (C 6H 5CC) with benzene (C 6H 6). Faraday Discuss 2024; 251:509-522. [PMID: 38766758 DOI: 10.1039/d3fd00159h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
The exploration of the fundamental formation mechanisms of polycyclic aromatic hydrocarbons (PAHs) is crucial for the understanding of molecular mass growth processes leading to two- and three-dimensional carbonaceous nanostructures (nanosheets, graphenes, nanotubes, buckyballs) in extraterrestrial environments (circumstellar envelopes, planetary nebulae, molecular clouds) and combustion systems. While key studies have been conducted exploiting traditional, high-temperature mechanisms such as the hydrogen abstraction-acetylene addition (HACA) and phenyl addition-dehydrocyclization (PAC) pathways, the complexity of extreme environments highlights the necessity of investigating chemically diverse mass growth reaction mechanisms leading to PAHs. Employing the crossed molecular beams technique coupled with electronic structure calculations, we report on the gas-phase synthesis of phenanthrene (C14H10)-a three-ring, 14π benzenoid PAH-via a phenylethynyl addition-cyclization-aromatization mechanism, featuring bimolecular reactions of the phenylethynyl radical (C6H5CC, X2A1) with benzene (C6H6) under single collision conditions. The dynamics involve a phenylethynyl radical addition to benzene without entrance barrier leading eventually to phenanthrene via indirect scattering dynamics through C14H11 intermediates. The barrierless nature of reaction allows rapid access to phenanthrene in low-temperature environments such as cold molecular clouds which can reach temperatures as low as 10 K. This mechanism constitutes a unique, low-temperature framework for the formation of PAHs as building blocks in molecular mass growth processes to carbonaceous nanostructures in extraterrestrial environments thus affording critical insight into the low-temperature hydrocarbon chemistry in our universe.
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Affiliation(s)
- Shane J Goettl
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, USA.
| | - Zhenghai Yang
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, USA.
| | - Chao He
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, USA.
| | - Ankit Somani
- Lehrstuhl für Organische Chemie II, Ruhr-Universität Bochum, 44801 Bochum, Germany.
| | | | - Wolfram Sander
- Lehrstuhl für Organische Chemie II, Ruhr-Universität Bochum, 44801 Bochum, Germany.
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA.
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, USA.
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2
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Cole TA, Davis SR, Flint AR, Fortenberry RC. Bridging the gap: viable reaction pathways from tetrahedrane to benzyne. Phys Chem Chem Phys 2024; 26:12510-12519. [PMID: 38619071 DOI: 10.1039/d3cp06199j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
The addition of sp-carbon-containing molecules to polycyclic sp3 tetrahedrane (c-C4H4) results in the formation of both o-benzyne (c-C6H4) and benzene (c-C6H6). Since both c-C6H4 and c-C6H6 have been detected in the interstellar medium (ISM), providing additional pathways for their possible astrochemical formation mechanisms can lead to the discovery of other molecules, such as c-C4H4, benzvalyne, and vinylidene (:CCH2). Addition of diatomic carbon (C2), the ethynyl radical (C2H), vinylidene, and acetylene (HCCH) to c-C4H4 is undertaken in individual pathways through high-level quantum chemical computations at the CCSD(T)-F12b/cc-pVTZ-F12 level of theory. The resulting C2 addition pathway proceeds barrierlessly through benzvalyne as an intermediate and reaches a true minimum at c-C6H4, but no leaving groups are produced which is required to dissipate excess energy within an interstellar chemical scheme. Similarly, the C2H addition to c-C4H4 produces benzvalyne as well as its related isomers. This pathway allows for the loss of a hydrogen leaving group to dissipate the resulting energy. Lastly, the HCCH and :CCH2 addition pathways follow through both benzvalene and benzvalyne in order to reach c-C6H6 (benzene) and c-C6H4 (o-benzyne) as well as H2 as the required leaving group. Although there is a barrier to the HCCH addition, the :CCH2 addition presents the contrary with only submerged barriers. These proposed mechanisms provide alternative possibilities for the formation of complex organic molecules in space.
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Affiliation(s)
- Taylor A Cole
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi, 38677, USA.
| | - Steven R Davis
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi, 38677, USA.
| | - Athena R Flint
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi, 38677, USA.
| | - Ryan C Fortenberry
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi, 38677, USA.
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3
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Nixon CA. The Composition and Chemistry of Titan's Atmosphere. ACS EARTH & SPACE CHEMISTRY 2024; 8:406-456. [PMID: 38533193 PMCID: PMC10961852 DOI: 10.1021/acsearthspacechem.2c00041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 11/02/2023] [Accepted: 02/02/2024] [Indexed: 03/28/2024]
Abstract
In this review I summarize the current state of knowledge about the composition of Titan's atmosphere and our current understanding of the suggested chemistry that leads to that observed composition. I begin with our present knowledge of the atmospheric composition, garnered from a variety of measurements including Cassini-Huygens, the Atacama Large Millimeter/submillimeter Array, and other ground- and space-based telescopes. This review focuses on the typical vertical profiles of gases at low latitudes rather than global and temporal variations. The main body of the review presents a chemical description of how complex molecules are believed to arise from simpler species, considering all known "stable" molecules-those that have been uniquely identified in the neutral atmosphere. The last section of the review is devoted to the gaps in our present knowledge of Titan's chemical composition and how further work may fill those gaps.
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Affiliation(s)
- Conor A. Nixon
- Planetary Systems Laboratory, NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, Maryland 20771, United
States
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4
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Medvedkov IA, Nikolayev AA, He C, Yang Z, Mebel AM, Kaiser RI. One Collision-Two Substituents: Gas-Phase Preparation of Xylenes under Single-Collision Conditions. Angew Chem Int Ed Engl 2023:e202315147. [PMID: 38072833 DOI: 10.1002/anie.202315147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Indexed: 12/21/2023]
Abstract
The fundamental reaction pathways to the simplest dialkylsubstituted aromatics-xylenes (C6 H4 (CH3 )2 )-in high-temperature combustion flames and in low-temperature extraterrestrial environments are still unknown, but critical to understand the chemistry and molecular mass growth processes in these extreme environments. Exploiting crossed molecular beam experiments augmented by state-of-the-art electronic structure and statistical calculations, this study uncovers a previously elusive, facile gas-phase synthesis of xylenes through an isomer-selective reaction of 1-propynyl (methylethynyl, CH3 CC) with 2-methyl-1,3-butadiene (isoprene, C5 H8 ). The reaction dynamics are driven by a barrierless addition of the radical to the diene moiety of 2-methyl-1,3-butadiene followed by extensive isomerization (hydrogen shifts, cyclization) prior to unimolecular decomposition accompanied by aromatization via atomic hydrogen loss. This overall exoergic reaction affords a preparation of xylenes not only in high-temperature environments such as in combustion flames and around circumstellar envelopes of carbon-rich Asymptotic Giant Branch (AGB) stars, but also in low-temperature cold molecular clouds (10 K) and in hydrocarbon-rich atmospheres of planets and their moons such as Triton and Titan. Our study established a hitherto unknown gas-phase route to xylenes and potentially more complex, disubstituted benzenes via a single collision event highlighting the significance of an alkyl-substituted ethynyl-mediated preparation of aromatic molecules in our Universe.
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Affiliation(s)
- Iakov A Medvedkov
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, HI 96822, USA
| | | | - Chao He
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, HI 96822, USA
| | - Zhenghai Yang
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, HI 96822, USA
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, HI 96822, USA
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5
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Falkowski AG, da Costa RF, Lima MAP, de A Cadena A, Pocoroba R, Jones R, Mathur M, Childers JG, Khakoo MA, Kossoski F. Electron impact electronic excitation of benzene: Theory and experiment. J Chem Phys 2023; 159:194301. [PMID: 37966005 DOI: 10.1063/5.0173024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Accepted: 10/03/2023] [Indexed: 11/16/2023] Open
Abstract
We report experimental differential cross sections (DCSs) for electron impact excitation of bands I to V of benzene at incident energies of 10, 12.5, 15, and 20 eV. They are compared to calculations using the Schwinger multichannel method while accounting for up to 437 open channels. For intermediate scattering angles, the calculations reveal that the most intense band (V) emerges from surprisingly similar contributions from all its underlying states (despite some preference for the dipole-allowed transitions). They further shed light on intricate multichannel couplings between the states of bands I to V and higher-lying Rydberg states. In turn, the measurements support a vibronic coupling mechanism for excitation of bands II and IV and also show an unexpected forward peak in the spin-forbidden transition accounting for band III. Overall, there is decent agreement between theory and experiment at intermediate angles and at lower energies and in terms of the relative DCSs of the five bands. Discrepancies between the present and previous experiment regarding bands IV and V draw attention to the need of additional experimental investigations. We also report measured DCSs for vibrational excitation of combined C-H stretching modes.
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Affiliation(s)
- Alan G Falkowski
- Instituto de Física "Gleb Wataghin," Universidade Estadual de Campinas, Campinas, Brazil
| | - Romarly F da Costa
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, 09210-580 Santo André, São Paulo, Brazil
| | - Marco A P Lima
- Instituto de Física "Gleb Wataghin," Universidade Estadual de Campinas, Campinas, Brazil
| | - Alexi de A Cadena
- Physics Department, California State University, Fullerton, California 92831, USA
| | - Ronald Pocoroba
- Physics Department, California State University, Fullerton, California 92831, USA
| | - Regan Jones
- Physics Department, California State University, Fullerton, California 92831, USA
| | - Mahak Mathur
- Troy High School, 2200 Dorothy Lane, Fullerton, California 92831, USA
| | - J G Childers
- Physics Department, California State University, Fullerton, California 92831, USA
| | - Murtadha A Khakoo
- Physics Department, California State University, Fullerton, California 92831, USA
| | - Fábris Kossoski
- Laboratoire de Chimie et Physique Quantiques (UMR 5626), Université de Toulouse, CNRS, UPS, 31062 Toulouse, France
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6
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Rap DB, Simon A, Steenbakkers K, Schrauwen JGM, Redlich B, Brünken S. Fingerprinting fragments of fragile interstellar molecules: dissociation chemistry of pyridine and benzonitrile revealed by infrared spectroscopy and theory. Faraday Discuss 2023; 245:221-244. [PMID: 37404008 PMCID: PMC10510038 DOI: 10.1039/d3fd00015j] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 03/22/2023] [Indexed: 07/06/2023]
Abstract
The cationic fragmentation products in the dissociative ionization of pyridine and benzonitrile have been studied by infrared action spectroscopy in a cryogenic ion trap instrument at the Free-Electron Lasers for Infrared eXperiments (FELIX) Laboratory. A comparison of the experimental vibrational fingerprints of the dominant cationic fragments with those from quantum chemical calculations revealed a diversity of molecular fragment structures. The loss of HCN/HNC is shown to be the major fragmentation channel for both pyridine and benzonitrile. Using the determined structures of the cationic fragments, potential energy surfaces have been calculated to elucidate the nature of the neutral fragment partner. In the fragmentation chemistry of pyridine, multiple non-cyclic structures are formed, whereas the fragmentation of benzonitrile dominantly leads to the formation of cyclic structures. Among the fragments are linear cyano-(di)acetylene˙+, methylene-cyclopropene˙+ and o- and m-benzyne˙+ structures, the latter possible building blocks in interstellar polycyclic aromatic hydrocarbon (PAH) formation chemistry. Molecular dynamics simulations using density functional based tight binding (MD/DFTB) were performed and used to benchmark and elucidate the different fragmentation pathways based on the experimentally determined structures. The implications of the difference in fragments observed for pyridine and benzonitrile are discussed in an astrochemical context.
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Affiliation(s)
- Daniël B Rap
- Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands.
| | - Aude Simon
- Laboratoire de Chimie et Physique Quantiques (LCPQ), Fédération FeRMI, CNRS & Université Toulouse III - Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse, France
| | - Kim Steenbakkers
- Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands.
| | - Johanna G M Schrauwen
- Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands.
| | - Britta Redlich
- Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands.
| | - Sandra Brünken
- Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands.
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7
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Yang Z, Galimova GR, He C, Goettl SJ, Paul D, Lu W, Ahmed M, Mebel AM, Li X, Kaiser RI. Gas-phase formation of the resonantly stabilized 1-indenyl (C 9H 7•) radical in the interstellar medium. SCIENCE ADVANCES 2023; 9:eadi5060. [PMID: 37682989 PMCID: PMC10491290 DOI: 10.1126/sciadv.adi5060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 08/07/2023] [Indexed: 09/10/2023]
Abstract
The 1-indenyl (C9H7•) radical, a prototype aromatic and resonantly stabilized free radical carrying a six- and a five-membered ring, has emerged as a fundamental molecular building block of nonplanar polycyclic aromatic hydrocarbons (PAHs) and carbonaceous nanostructures in deep space and combustion systems. However, the underlying formation mechanisms have remained elusive. Here, we reveal an unconventional low-temperature gas-phase formation of 1-indenyl via barrierless ring annulation involving reactions of atomic carbon [C(3P)] with styrene (C6H5C2H3) and propargyl (C3H3•) with phenyl (C6H5•). Macroscopic environments like molecular clouds act as natural low-temperature laboratories, where rapid molecular mass growth to 1-indenyl and subsequently complex PAHs involving vinyl side-chained aromatics and aryl radicals can occur. These reactions may account for the formation of PAHs and their derivatives in the interstellar medium and carbonaceous chondrites and could close the gap of timescales of their production and destruction in our carbonaceous universe.
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Affiliation(s)
- Zhenghai Yang
- Department of Chemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822, USA
| | - Galiya R. Galimova
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Chao He
- Department of Chemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822, USA
| | - Shane J. Goettl
- Department of Chemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822, USA
| | - Dababrata Paul
- Department of Chemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822, USA
| | - Wenchao Lu
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Musahid Ahmed
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Alexander M. Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Xiaohu Li
- Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi, Xinjiang 830011, P. R. China
- Key Laboratory of Radio Astronomy, Chinese Academy of Sciences, Urumqi, Xinjiang 830011, P. R. China
| | - Ralf I. Kaiser
- Department of Chemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822, USA
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8
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He C, Kaiser RI, Lu W, Ahmed M, Krasnoukhov VS, Pivovarov PS, Zagidullin MV, Azyazov VN, Morozov AN, Mebel AM. Unconventional gas-phase preparation of the prototype polycyclic aromatic hydrocarbon naphthalene (C 10H 8) via the reaction of benzyl (C 7H 7) and propargyl (C 3H 3) radicals coupled with hydrogen-atom assisted isomerization. Chem Sci 2023; 14:5369-5378. [PMID: 37234886 PMCID: PMC10208037 DOI: 10.1039/d3sc00911d] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 04/19/2023] [Indexed: 05/28/2023] Open
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the interstellar medium and in meteorites such as Murchison and Allende and signify the missing link between resonantly stabilized free radicals and carbonaceous nanoparticles (soot particles, interstellar grains). However, the predicted lifetime of interstellar PAHs of some 108 years imply that PAHs should not exist in extraterrestrial environments suggesting that key mechanisms of their formation are elusive. Exploiting a microchemical reactor and coupling these data with computational fluid dynamics (CFD) simulations and kinetic modeling, we reveal through an isomer selective product detection that the reaction of the resonantly stabilized benzyl and the propargyl radicals synthesizes the simplest representative of PAHs - the 10π Hückel aromatic naphthalene (C10H8) molecule - via the novel Propargyl Addition-BenzAnnulation (PABA) mechanism. The gas-phase preparation of naphthalene affords a versatile concept of the reaction of combustion and astronomically abundant propargyl radicals with aromatic radicals carrying the radical center at the methylene moiety as a previously passed over source of aromatics in high temperature environments thus bringing us closer to an understanding of the aromatic universe we live in.
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Affiliation(s)
- Chao He
- Department of Chemistry, University of Hawai'i at Mānoa Honolulu HI 96822 USA
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Mānoa Honolulu HI 96822 USA
| | - Wenchao Lu
- Chemical Sciences Division, Lawrence Berkeley National Laboratory Berkeley CA 94720 USA
| | - Musahid Ahmed
- Chemical Sciences Division, Lawrence Berkeley National Laboratory Berkeley CA 94720 USA
| | - Vladislav S Krasnoukhov
- Lebedev Physical Institute Samara 443011 Russian Federation
- Samara National Research University Samara 443086 Russian Federation
| | - Pavel S Pivovarov
- Samara National Research University Samara 443086 Russian Federation
| | | | | | - Alexander N Morozov
- Department of Chemistry and Biochemistry, Florida International University Miami Florida 33199 USA
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University Miami Florida 33199 USA
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9
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Yang Z, Galimova GR, He C, Doddipatla S, Mebel AM, Kaiser RI. Gas-Phase Formation of 1,3,5,7-Cyclooctatetraene (C 8H 8) through Ring Expansion via the Aromatic 1,3,5-Cyclooctatrien-7-yl Radical (C 8H 9•) Transient. J Am Chem Soc 2022; 144:22470-22478. [PMID: 36454210 DOI: 10.1021/jacs.2c06448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Gas-phase 1,3,5,7-cyclooctatetraene (C8H8) and triplet aromatic 1,3,5,7-cyclooctatetraene (C8H8) were formed for the first time through bimolecular methylidyne radical (CH)-1,3,5-cycloheptatriene (C7H8) reactions under single-collision conditions on a doublet surface. The reaction involves methylidyne radical addition to the olefinic π electron system of 1,3,5-cycloheptatriene followed by isomerization and ring expansion to an aromatic 1,3,5-cyclooctatrien-7-yl radical (C8H9•). The chemically activated doublet radical intermediate undergoes unimolecular decomposition to 1,3,5,7-cyclooctatetraene. Substituted 1,3,5,7-cyclooctatetraene molecules can be prepared in the gas phase with hydrogen atom(s) in the 1,3,5-cycloheptatriene reactant being replaced by organic side groups. These findings are also of potential interest to organometallic chemists by expanding the synthesis of exotic transition-metal complexes incorporating substituted 1,3,5,7-cyclooctatetraene dianion (C8H82-) ligands and to untangle the unimolecular decomposition of chemically activated and substituted 1,3,5-cyclooctatrien-7-yl radical, eventually gaining a fundamental insight of their bonding chemistry, electronic structures, and stabilities.
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Affiliation(s)
- Zhenghai Yang
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii96822, United States
| | - Galiya R Galimova
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida33199, United States
| | - Chao He
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii96822, United States
| | - Srinivas Doddipatla
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii96822, United States
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida33199, United States
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii96822, United States
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10
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Krikunova LI, Nikolayev AA, Porfiriev DP, Mebel AM. Reaction of propionitrile with methylidyne: A theoretical study. J CHIN CHEM SOC-TAIP 2022. [DOI: 10.1002/jccs.202200461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Affiliation(s)
- Lubov I. Krikunova
- Samara National Research University Samara Russia
- Lebedev Physical Institute Samara Branch Samara Russia
| | - Anatoliy A. Nikolayev
- Samara National Research University Samara Russia
- Lebedev Physical Institute Samara Branch Samara Russia
| | - Denis P. Porfiriev
- Samara National Research University Samara Russia
- Lebedev Physical Institute Samara Branch Samara Russia
| | - Alexander M. Mebel
- Department of Chemistry and Biochemistry Florida International University Miami Florida USA
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11
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Kaiser RI, Zhao L, Lu W, Ahmed M, Evseev MM, Azyazov VN, Mebel AM, Mohamed RK, Fischer FR, Li X. Gas-phase synthesis of racemic helicenes and their potential role in the enantiomeric enrichment of sugars and amino acids in meteorites. Phys Chem Chem Phys 2022; 24:25077-25087. [PMID: 36056687 DOI: 10.1039/d2cp03084e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The molecular origins of homochirality on Earth is not understood well, particularly how enantiomerically enriched molecules of astrobiological significance like sugars and amino acids might have been synthesized on icy grains in space preceding their delivery to Earth. Polycyclic aromatic hydrocarbons (PAHs) identified in carbonaceous chondrites could have been processed in molecular clouds by circularly polarized light prior to the depletion of enantiomerically enriched helicenes onto carbonaceous grains resulting in chiral islands. However, the fundamental low temperature reaction mechanisms leading to racemic helicenes are still unknown. Here, by exploiting synchrotron based molecular beam photoionization mass spectrometry combined with electronic structure calculations, we provide compelling testimony on barrierless, low temperature pathways leading to racemates of [5] and [6]helicene. Astrochemical modeling advocates that gas-phase reactions in molecular clouds lead to racemates of helicenes suggesting a pathway for future astronomical observation and providing a fundamental understanding for the origin of homochirality on early Earth.
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Affiliation(s)
- Ralf I Kaiser
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii, 96822, USA.
| | - Long Zhao
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii, 96822, USA.
| | - Wenchao Lu
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
| | - Musahid Ahmed
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
| | | | | | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA.
| | - Rana K Mohamed
- Department of Chemistry, University of California, Berkeley, CA 94720, USA.,Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.,Kavli Energy Nano Sciences Institute at the University of California Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Felix R Fischer
- Department of Chemistry, University of California, Berkeley, CA 94720, USA.,Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.,Kavli Energy Nano Sciences Institute at the University of California Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Xiaohu Li
- Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi, Xinjiang 830011, P. R. China.,Key Laboratory of Radio Astronomy, Chinese Academy of Sciences, Urumqi, Xinjiang 830011, P. R. China.
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12
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Poland KN, Yang W, Fortenberry RC, Davis SR. The thermal isomerization of benzvalyne to benzyne. Phys Chem Chem Phys 2022; 24:14573-14578. [PMID: 35666233 DOI: 10.1039/d2cp00794k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The isomerization of the highly strained benzvalyne structure to o-benzyne has been investigated using MCSCF and CCSD(T) levels of theory. Two reaction channels were modeled: the disrotatory one which leads directly to the benzyne product, and the conrotatory one which leads to an intermediate which can subsequently lead to the benzyne product. Energies at the MRMP2 level give 22.9 kcal mol-1 for the disrotatory channel and 21.7 and 1.4 kcal mol-1 for the two steps in the conrotatory one. However, the CCSD(T) energies give 19.3 and 14.2 kcal mol-1 for the two conrotatory steps. The first step of the conrotatory channel is significantly higher than the second so is rate determining for this channel. Comparison of the two separate channels shows that the conrotatory has just a slight energetic edge of 1.2 kcal mol-1 at the MRMP2 level. We did not compute the disrotatory channel at the CCSD(T) level due to the significant biradical nature of the wavefunction with natural orbital occupation numbers of 1.2 and 0.8 in the active space.
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Affiliation(s)
- Kimberley N Poland
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi, USA.
| | - Weiwei Yang
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi, USA.
| | - Ryan C Fortenberry
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi, USA.
| | - Steven R Davis
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi, USA.
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13
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Goettl SJ, He C, Paul D, Nikolayev AA, Azyazov VN, Mebel AM, Kaiser RI. Gas-Phase Study of the Elementary Reaction of the D1-Ethynyl Radical (C 2D; X 2Σ +) with Propylene (C 3H 6; X 1A') under Single-Collision Conditions. J Phys Chem A 2022; 126:1889-1898. [PMID: 35289624 DOI: 10.1021/acs.jpca.2c00297] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The bimolecular gas-phase reactions of the D1-ethynyl radical (C2D; X2Σ+) with propylene (C3H6; X1A') and partially substituted D3-3,3,3-propylene (C2H3CD3; X1A') were studied under single collision conditions utilizing the crossed molecular beams technique. Combining our laboratory data with electronic structure and statistical calculations, the D1-ethynyl radical is found to add without barrier to the C1 and C2 carbons of the propylene reactant, resulting in doublet C5H6D intermediate(s) with lifetime(s) longer than their rotational period(s). These intermediates undergo isomerization and unimolecular decomposition via atomic hydrogen loss through tight exit transition states forming predominantly cis/trans-3-penten-1-yne ((HCC)CH═CH(CH3)) and, to a minor amount, 3-methyl-3-buten-1-yne ((HCC)C(CH3)═CH2) via overall exoergic reactions. Although the title reaction does not lead to the cyclopentadiene molecule (c-C5H6, X1A1), high-temperature environments can convert the identified acyclic C5H6 isomers through hydrogen atom assisted isomerization to cyclopentadiene (c-C5H6, X1A1). Since both the ethynyl radical and propylene reactants have been observed in cold interstellar environments such as TMC-1 and the reaction is exoergic and all barriers lie below the energy of the separated reactants, these C5H6 product isomers are predicted to form in those low-temperature regions.
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Affiliation(s)
- Shane J Goettl
- Department of Chemistry, University of Hawai'i at Ma̅noa, Honolulu, Hawaii 96822, United States
| | - Chao He
- Department of Chemistry, University of Hawai'i at Ma̅noa, Honolulu, Hawaii 96822, United States
| | - Dababrata Paul
- Department of Chemistry, University of Hawai'i at Ma̅noa, Honolulu, Hawaii 96822, United States
| | - Anatoliy A Nikolayev
- Lebedev Physical Institute, Samara 443011, Russian Federation.,Samara National Research University, Samara 443086, Russian Federation
| | - Valeriy N Azyazov
- Lebedev Physical Institute, Samara 443011, Russian Federation.,Samara National Research University, Samara 443086, Russian Federation
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Ma̅noa, Honolulu, Hawaii 96822, United States
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14
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Jiang Y, Song J, Zhu A. Gas-phase advanced oxidation (GPAO) for benzene-containing gas by an ultraviolet irradiation/hydrogen peroxide vapour (UV/[H 2O 2] g) process. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:16418-16426. [PMID: 34648160 PMCID: PMC8514807 DOI: 10.1007/s11356-021-16920-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Accepted: 10/03/2021] [Indexed: 05/24/2023]
Abstract
Hydrogen peroxide (H2O2) is a remarkably strong oxidant, and its vapour ([H2O2]g) has further advantages, such as a low cost and good light transmission. However, there has been very little research on its removal through gas-phase advanced oxidation (GPAO). In the present study, the photochemical oxidation of a gas that contains a series of benzene derivatives using ultraviolet (UV) irradiation and [H2O2]g was investigated in a transparent bag made of fluorinated ethylene propylene (FEP). UV and [H2O2]g barely reduced the pollutant within 5 h when used alone, and the reactant was also stable. When the pollutant concentration was high (248 to 756 mg/m3) and the residence time was short (3 s) compared with related studies on the removal of benzene, toluene and xylene, the apparent removal rate by UV/[H2O2]g/(powder active carbon, PAC) was higher than when other methods (UV/[H2O2]g, UV/[H2O2]g/TiO2 and UV/[H2O2]g/ZnO), were used. However, it was found that the mineralization by UV/[H2O2]g significantly decreased, which in turn decreased the conductivity after the reaction. Increasing the pollutant concentration and the pH of the H2O2 had a negative effect on the treatment, but the UV radiation had a positive effect at powers of up to 40 W. In addition, the characteristic absorbance of three benzene derivatives showed that the key structure of the pollutant molecules was damaged during GPAO.
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Affiliation(s)
- Yuping Jiang
- University of Electronic Science and Technology of China, Zhongshan Institute, Zhongshan City, 528403, Guangdong Province, China.
| | - Juanjuan Song
- University of Electronic Science and Technology of China, Zhongshan Institute, Zhongshan City, 528403, Guangdong Province, China
| | - Andong Zhu
- University of Electronic Science and Technology of China, Zhongshan Institute, Zhongshan City, 528403, Guangdong Province, China
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15
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Nguyen TL, Bross DH, Ruscic B, Ellison GB, Stanton J. Mechanism, Thermochemistry, and Kinetics of the Reversible Reactions: C2H3 + H2 ⇌ C2H4 + H ⇌ C2H5. Faraday Discuss 2022; 238:405-430. [DOI: 10.1039/d1fd00124h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
High-level coupled cluster theory, in conjunction with Active Thermochemical Tables (ATcT) and E,J-resolved master equation calculations were used in a study of the title reactions, which play an important role...
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16
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He C, Yang Z, Doddipatla S, Thomas AM, Kaiser RI, Galimova GR, Mebel AM, Fujioka K, Sun R. Directed gas phase preparation of ethynylallene (H 2CCCHCCH; X 1A′) via the crossed molecular beam reaction of the methylidyne radical (CH; X 2Π) with vinylacetylene (H 2CCHCCH; X 1A′). Phys Chem Chem Phys 2022; 24:26499-26510. [DOI: 10.1039/d2cp04081f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The elementary reaction of the methylidyne radical with vinylacetylene leading to the predominant formation of ethynylallene and atomic hydrogen via indirect scattering dynamics.
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Affiliation(s)
- Chao He
- Department of Chemistry, University of Hawai‘i at Mānoa, Honolulu, HI 96822, USA
| | - Zhenghai Yang
- Department of Chemistry, University of Hawai‘i at Mānoa, Honolulu, HI 96822, USA
| | - Srinivas Doddipatla
- Department of Chemistry, University of Hawai‘i at Mānoa, Honolulu, HI 96822, USA
| | - Aaron M. Thomas
- Department of Chemistry, University of Hawai‘i at Mānoa, Honolulu, HI 96822, USA
| | - Ralf I. Kaiser
- Department of Chemistry, University of Hawai‘i at Mānoa, Honolulu, HI 96822, USA
| | - Galiya R. Galimova
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA
| | - Alexander M. Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA
| | - Kazuumi Fujioka
- Department of Chemistry, University of Hawai‘i at Mānoa, Honolulu, HI 96822, USA
| | - Rui Sun
- Department of Chemistry, University of Hawai‘i at Mānoa, Honolulu, HI 96822, USA
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17
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He C, Fujioka K, Nikolayev AA, Zhao L, Doddipatla S, Azyazov VN, Mebel AM, Sun R, Kaiser RI. A chemical dynamics study of the reaction of the methylidyne radical (CH, X 2Π) with dimethylacetylene (CH 3CCCH 3, X 1A 1g). Phys Chem Chem Phys 2021; 24:578-593. [PMID: 34908056 DOI: 10.1039/d1cp04443e] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The gas-phase reaction of the methylidyne (CH; X2Π) radical with dimethylacetylene (CH3CCCH3; X1A1g) was studied at a collision energy of 20.6 kJ mol-1 under single collision conditions with experimental results merged with ab initio calculations of the potential energy surface (PES) and ab initio molecule dynamics (AIMD) simulations. The crossed molecular beam experiment reveals that the reaction proceeds barrierless via indirect scattering dynamics through long-lived C5H7 reaction intermediate(s) ultimately dissociating to C5H6 isomers along with atomic hydrogen with atomic hydrogen predominantly released from the methyl groups as verified by replacing the methylidyne with the D1-methylidyne reactant. AIMD simulations reveal that the reaction dynamics are statistical leading predominantly to p28 (1-methyl-3-methylenecyclopropene, 13%) and p8 (1-penten-3-yne, 81%) plus atomic hydrogen with a significant amount of available energy being channeled into the internal excitation of the polyatomic reaction products. The dynamics are controlled by addition to the carbon-carbon triple bond with the reaction intermediates eventually eliminating a hydrogen atom from the methyl groups of the dimethylacetylene reactant forming 1-methyl-3-methylenecyclopropene (p28). The dominating pathways reveal an unexpected insertion of methylidyne into one of the six carbon-hydrogen single bonds of the methyl groups of dimethylacetylene leading to the acyclic intermediate, which then decomposes to 1-penten-3-yne (p8). Therefore, the methyl groups of dimethylacetylene effectively 'screen' the carbon-carbon triple bond from being attacked by addition thus directing the dynamics to an insertion process as seen exclusively in the reaction of methylidyne with ethane (C2H6) forming propylene (CH3C2H3). Therefore, driven by the screening of the triple bond, one propynyl moiety (CH3CC) acts in four out of five trajectories as a spectator thus driving an unexpected, but dominating chemistry in analogy to the methylidyne - ethane system.
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Affiliation(s)
- Chao He
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, USA.
| | - Kazuumi Fujioka
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, USA.
| | - Anatoliy A Nikolayev
- Lebedev Physical Institute, Samara 443011, Russia.,Samara National Research University, Samara 443086, Russia
| | - Long Zhao
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, USA.
| | - Srinivas Doddipatla
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, USA.
| | - Valeriy N Azyazov
- Lebedev Physical Institute, Samara 443011, Russia.,Samara National Research University, Samara 443086, Russia
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA.
| | - Rui Sun
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, USA.
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, USA.
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18
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Monluc L, Nikolayev AA, Medvedkov IA, Azyazov VN, Morozov AN, Mebel AM. The Reaction of o-Benzyne with Vinylacetylene: An Unexplored Way to Produce Naphthalene. Chemphyschem 2021; 23:e202100758. [PMID: 34767677 DOI: 10.1002/cphc.202100758] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/12/2021] [Indexed: 11/09/2022]
Abstract
The mechanism and kinetics of the reaction of ortho-benzyne with vinylacetylene have been studied by ab initio and density functional CCSD(T)-F12/cc-pVTZ-f12//B3LYP/6-311G(d,p) calculations of the pertinent potential energy surface combined with Rice-Ramsperger-Kassel-Marcus - Master Equation calculations of reaction rate constants at various temperatures and pressures. Under prevailing combustion conditions, the reaction has been shown to predominantly proceed by the biradical acetylenic mechanism initiated by the addition of C4 H4 to one of the C atoms of the triple bond in ortho-benzyne by the acetylenic end, with a significant contribution of the concerted addition mechanism. Following the initial reaction steps, an extra six-membered ring is produced and the rearrangement of H atoms in this new ring leads to the formation of naphthalene, which can further dissociate to 1- or 2-naphthyl radicals. The o-C6 H4 +C4 H4 reaction is highly exothermic, by ∼143 kcal/mol to form naphthalene and by 31-32 kcal mol-1 to produce naphthyl radicals plus H, but features relatively high entrance barriers of 9-11 kcal mol-1 . Although the reaction is rather slow, much slower than the reaction of phenyl radical with vinylacetylene, it forms naphthalene and 1- and 2-naphthyl radicals directly, with their relative yields controlled by the temperature and pressure, and thus represents a viable source of the naphthalene core under conditions where ortho-benzyne and vinylacetylene are available.
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Affiliation(s)
- Lisa Monluc
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, 33199, USA.,Present address: Department of Chemistry and Biochemistry, Florida State University, 102 Varsity Way, Tallahassee, FI, 32306, USA
| | - Anatoliy A Nikolayev
- Samara National Research University, Samara, 443086, Russia.,Lebedev Physical Institute, Samara, 443011, Russia
| | - Iakov A Medvedkov
- Samara National Research University, Samara, 443086, Russia.,Lebedev Physical Institute, Samara, 443011, Russia
| | - Valeriy N Azyazov
- Samara National Research University, Samara, 443086, Russia.,Lebedev Physical Institute, Samara, 443011, Russia
| | - Alexander N Morozov
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, 33199, USA
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, 33199, USA
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19
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Nikolayev AA, Azyazov VN, Kaiser RI, Mebel AM. Theoretical Study of the Reaction of the Methylidyne Radical (CH; X 2Π) with 1-Butyne (CH 3CH 2CCH; X 1A'). J Phys Chem A 2021; 125:9536-9547. [PMID: 34672597 DOI: 10.1021/acs.jpca.1c07519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ab initio CCSD(T)-F12/cc-pVTZ-f12//ωB97X-D/6-311G(d,p) + ZPE[ωB97X-D/6-311G(d,p)] calculations were carried out to unravel the area of the C5H7 potential energy surface accessed by the reaction of the methylidyne radical with 1-butyne. The results were utilized in Rice-Ramsperger-Kassel-Marcus calculations of the product branching ratios at the zero pressure limit. The preferable reaction mechanism has been shown to involve (nearly) instantaneous decomposition of the initial reaction adducts, whose structures are controlled by the isomeric form of the C4H6 reactant. If CH adds to the triple C≡C bond in the entrance reaction channel, the reaction is predicted to predominantly form the methylenecyclopropene + methyl (CH3) and cyclopropenylidene + ethyl (C2H5) products roughly in a 2:1 ratio. CH insertion into a C-H bond in the methyl group of 1-butyne is anticipated to preferentially form ethylene + propargyl (C3H3) by the C-C bond β-scission in the initial complex, whereas CH insertion into C-H of the CH2 group would predominantly produce vinylacetylene + methyl (CH3) also by the C-C bond β-scission in the adduct. The barrierless and highly exoergic CH + 1-butyne reaction, facile in cold molecular clouds, is not likely to lead to the carbon skeleton molecular growth but generates C4H4 isomers methylenecyclopropene, vinylacetylene, and 1,2,3-butatriene and smaller C2 and C3 hydrocarbons such as methyl, ethyl, and propargyl radicals, ethylene, and cyclopropenylidene.
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Affiliation(s)
- Anatoliy A Nikolayev
- Lebedev Physical Institute, Samara 443011, Russian Federation.,Samara National Research University, Samara 443086, Russian Federation
| | - Valeriy N Azyazov
- Lebedev Physical Institute, Samara 443011, Russian Federation.,Samara National Research University, Samara 443086, Russian Federation
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
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20
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Zhao L, Prendergast M, Kaiser RI, Xu B, Lu W, Ahmed M, Hasan Howlader A, Wnuk SF, Korotchenko AS, Evseev MM, Bashkirov EK, Azyazov VN, Mebel AM. A molecular beam and computational study on the barrierless gas phase formation of (iso)quinoline in low temperature extraterrestrial environments. Phys Chem Chem Phys 2021; 23:18495-18505. [PMID: 34612388 DOI: 10.1039/d1cp02169a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Despite remarkable progress toward the understanding of the formation pathways leading to polycyclic aromatic hydrocarbons (PAHs) in combustion systems and in deep space, the complex reaction pathways leading to nitrogen-substituted PAHs (NPAHs) at low temperatures of molecular clouds and hydrocarbon-rich, nitrogen-containing atmospheres of planets and their moons like Titan have remained largely obscure. Here, we demonstrate through laboratory experiments and computations that the simplest prototype of NPAHs - quinoline and isoquinoline (C9H7N) - can be synthesized via rapid and de-facto barrier-less reactions involving o-, m- and p-pyridinyl radicals (C5H4N˙) with vinylacetylene (C4H4) under low-temperature conditions.
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Affiliation(s)
- Long Zhao
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA.
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21
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He C, Goettl SJ, Yang Z, Doddipatla S, Kaiser RI, Silva MX, Galvão BRL. Directed gas-phase preparation of the elusive phosphinosilylidyne (SiPH 2, X 2A'') and cis/trans phosphinidenesilyl (HSiPH; X 2A') radicals under single-collision conditions. Phys Chem Chem Phys 2021; 23:18506-18516. [PMID: 34612389 DOI: 10.1039/d1cp02812j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The reaction of the D1-silylidyne radical (SiD; X2Π) with phosphine (PH3; X1A1) was conducted in a crossed molecular beams machine under single collision conditions. Merging of the experimental results with ab initio electronic structure and statistical Rice-Ramsperger-Kassel-Marcus (RRKM) calculations indicates that the reaction is initiated by the barrierless formation of a van der Waals complex (i0) as well as intermediate (i1) formed via the barrierless addition of the SiD radical with its silicon atom to the non-bonding electron pair of phosphorus of the phosphine. Hydrogen shifts from the phosphorous atom to the adjacent silicon atom yield intermediates i2a, i2b, i3; unimolecular decomposition of these intermediates leads eventually to the formation of trans/cis-phosphinidenesilyl (HSiPH, p2/p4) and phosphinosilylidyne (SiPH2, p3) via hydrogen deuteride (HD) loss (experiment: 80 ± 11%, RRKM: 68.7%) and d-trans/cis-phosphinidenesilyl (DSiPH, p2'/p4') plus molecular hydrogen (H2) (experiment: 20 ± 7%, RRKM: 31.3%) through indirect scattering dynamics via tight exit transition states. Overall, the study reveals branching ratios of p2/p4/p2'/p4' (trans/cis HSiPH/DSiPH) to p3 (SiPH2) of close to 4 : 1. The present study sheds light on the complex reaction dynamics of the silicon and phosphorous systems involving multiple atomic hydrogen migrations and tight exit transition states, thus opening up a versatile path to access the previously elusive phosphinidenesilyl and phosphinosilylidyne doublet radicals, which represent potential targets of future astronomical searches toward cold molecular clouds (TMC-1), star forming regions (Sgr(B2)), and circumstellar envelopes of carbon rich stars (IRC + 10216).
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Affiliation(s)
- Chao He
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, USA.
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22
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Goettl SJ, Yang Z, Doddipatla S, He C, Alves MO, Galvão BRL, Kaiser RI. A Crossed Molecular Beams and Computational Study of the Formation of the Astronomically Elusive Thiosilaformyl Radical (HSiS, X 2A'). J Phys Chem Lett 2021; 12:5979-5986. [PMID: 34161096 DOI: 10.1021/acs.jpclett.1c01706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The formation pathways to silicon- and sulfur-containing molecules are crucial to the understanding of silicon-sulfur chemistry in interstellar and circumstellar environments. While multiple silicon- and sulfur-containing species have been observed in deep space, their fundamental formation mechanisms are largely unknown. The crossed molecular beams technique combined with electronic structure and Rice-Ramsperger-Kassel-Marcus (RRKM) calculations was utilized to study the bimolecular reaction of atomic silicon (Si(3Pj)) with thiomethanol (CH3SH, X1A') leading to the thiosilaformyl radical (HSiS, X2A') via an exclusive methyl radical (CH3, X2A2″) loss via indirect scattering dynamics which involves barrierless addition and hydrogen migration in an overall exoergic reaction, indicating the possibility that HSiS can form in cold molecular clouds. The astronomically elusive thiosilaformyl radical may act as a tracer of an exotic silicon-sulfur chemistry to be deciphered toward, for example, the star-forming region SgrB2, thus leading to a better understanding of the formation of silicon-sulfur bonds in deep space.
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Affiliation(s)
- Shane J Goettl
- Department of Chemistry, University of Hawai'i at Ma̅noa, Honolulu, Hawaii 96822, United States
| | - Zhenghai Yang
- Department of Chemistry, University of Hawai'i at Ma̅noa, Honolulu, Hawaii 96822, United States
| | - Srinivas Doddipatla
- Department of Chemistry, University of Hawai'i at Ma̅noa, Honolulu, Hawaii 96822, United States
| | - Chao He
- Department of Chemistry, University of Hawai'i at Ma̅noa, Honolulu, Hawaii 96822, United States
| | - Márcio O Alves
- Centro Federal de Educação Tecnológica de Minas Gerais, CEFET-MG, Av. Amazonas 5253, 30421-169 Belo Horizonte, Minas Gerais, Brazil
| | - Breno R L Galvão
- Centro Federal de Educação Tecnológica de Minas Gerais, CEFET-MG, Av. Amazonas 5253, 30421-169 Belo Horizonte, Minas Gerais, Brazil
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Ma̅noa, Honolulu, Hawaii 96822, United States
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23
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Krasnoukhov VS, Azyazov VN, Mebel AM, Doddipatla S, Yang Z, Goettl S, Kaiser RI. Combined Crossed Molecular Beams and Ab Initio Study of the Bimolecular Reaction of Ground State Atomic Silicon (Si; 3 P) with Germane (GeH 4 ; X 1 A 1 ). Chemphyschem 2021; 22:1497-1504. [PMID: 34004053 DOI: 10.1002/cphc.202100235] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 04/30/2021] [Indexed: 11/09/2022]
Abstract
The chemical dynamics of the elementary reaction of ground state atomic silicon (Si; 3 P) with germane (GeH4 ; X1 A1 ) were unraveled in the gas phase under single collision condition at a collision energy of 11.8±0.3 kJ mol-1 exploiting the crossed molecular beams technique contemplated with electronic structure calculations. The reaction follows indirect scattering dynamics and is initiated through an initial barrierless insertion of the silicon atom into one of the four chemically equivalent germanium-hydrogen bonds forming a triplet collision complex (HSiGeH3 ; 3 i1). This intermediate underwent facile intersystem crossing (ISC) to the singlet surface (HSiGeH3 ; 1 i1). The latter isomerized via at least three hydrogen atom migrations involving exotic, hydrogen bridged reaction intermediates eventually leading to the H3 SiGeH isomer i5. This intermediate could undergo unimolecular decomposition yielding the dibridged butterfly-structured isomer 1 p1 (Si(μ-H2 )Ge) plus molecular hydrogen through a tight exit transition state. Alternatively, up to two subsequent hydrogen shifts to i6 and i7, followed by fragmentation of each of these intermediates, could also form 1 p1 (Si(μ-H2 )Ge) along with molecular hydrogen. The overall non-adiabatic reaction dynamics provide evidence on the existence of exotic dinuclear hydrides of main group XIV elements, whose carbon analog structures do not exist.
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Affiliation(s)
- Vladislav S Krasnoukhov
- Samara National Research University, Samara, 443086.,Lebedev Physical Institute, Samara, 443011, Russian Federation
| | - Valeriy N Azyazov
- Samara National Research University, Samara, 443086.,Lebedev Physical Institute, Samara, 443011, Russian Federation
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA.,Samara National Research University, Samara, 443086
| | - Srinivas Doddipatla
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA
| | - Zhenghai Yang
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA
| | - Shane Goettl
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA
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24
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Zhao L, Lu W, Ahmed M, Zagidullin MV, Azyazov VN, Morozov AN, Mebel AM, Kaiser RI. Gas-phase synthesis of benzene via the propargyl radical self-reaction. SCIENCE ADVANCES 2021; 7:7/21/eabf0360. [PMID: 34020951 PMCID: PMC8139581 DOI: 10.1126/sciadv.abf0360] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 03/31/2021] [Indexed: 06/01/2023]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) have been invoked in fundamental molecular mass growth processes in our galaxy. We provide compelling evidence of the formation of the very first ringed aromatic and building block of PAHs-benzene-via the self-recombination of two resonantly stabilized propargyl (C3H3) radicals in dilute environments using isomer-selective synchrotron-based mass spectrometry coupled to theoretical calculations. Along with benzene, three other structural isomers (1,5-hexadiyne, fulvene, and 2-ethynyl-1,3-butadiene) and o-benzyne are detected, and their branching ratios are quantified experimentally and verified with the aid of computational fluid dynamics and kinetic simulations. These results uncover molecular growth pathways not only in interstellar, circumstellar, and solar systems environments but also in combustion systems, which help us gain a better understanding of the hydrocarbon chemistry of our universe.
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Affiliation(s)
- Long Zhao
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA
| | - Wenchao Lu
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Musahid Ahmed
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
| | | | - Valeriy N Azyazov
- Lebedev Physical Institute, Samara 443011, Russian Federation
- Samara National Research University, Samara 443086, Russian Federation
| | - Alexander N Morozov
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA.
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA.
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25
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Bourgalais J, Carrasco N, Vettier L, Comby A, Descamps D, Petit S, Blanchet V, Gaudin J, Mairesse Y, Marty B. Aromatic Formation Promoted by Ion-Driven Radical Pathways in EUV Photochemical Experiments Simulating Titan's Atmospheric Chemistry. J Phys Chem A 2021; 125:3159-3168. [PMID: 33843236 DOI: 10.1021/acs.jpca.1c00324] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the atmosphere of Titan, Saturn's main satellite, molecular growth is initiated by 85.6 nm extreme ultraviolet (EUV) photons triggering a chemistry with charged and free-radical species. However, the respective contribution of these species to the complexification of matter is far from being known. This work presents a chemical analysis in order to contribute to a better understanding of aromatic formation pathways. A gas mixture of N2/CH4 (90/10%) within the closed SURFACAT reactor was irradiated at a relatively low pressure (0.1 mbar) and room temperature for 6 h by EUV photons (∼85.6 nm). The neutral molecules formed at the end of the irradiation were condensed in a cryogenic trap and analyzed by electron ionization mass spectrometry. An analysis of the dominant chemical pathways highlights the identification of benzene and toluene and underlies the importance of small ion and radical reactions. On the basis of the experimental results, a speculative mechanism based on sequential H-elimination/CH3-addition reactions is proposed for the growth of aromatics in Titan's atmosphere. Elementary reactions to be studied are given to instill future updates of photochemical models of Titan's atmosphere.
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Affiliation(s)
- Jérémy Bourgalais
- LATMOS-IPSL, Université Versailles St-Quentin, CNRS/INSU, Sorbonne Université, UPMC Univ. Paris 06, 11 boulevard d'Alembert, 78280 Guyancourt, France.,Centre de Recherches Pétrographiques et Géochimiques, UMR 7358 CNRS-Université de Lorraine, 15 rue Notre Dame des Pauvres, BP 20, F-54501 Vandoeuvre-lès-Nancy, France
| | - Nathalie Carrasco
- LATMOS-IPSL, Université Versailles St-Quentin, CNRS/INSU, Sorbonne Université, UPMC Univ. Paris 06, 11 boulevard d'Alembert, 78280 Guyancourt, France
| | - Ludovic Vettier
- LATMOS-IPSL, Université Versailles St-Quentin, CNRS/INSU, Sorbonne Université, UPMC Univ. Paris 06, 11 boulevard d'Alembert, 78280 Guyancourt, France
| | - Antoine Comby
- CELIA, Université de Bordeaux - CNRS - CEA, UMR5107, 351 Cours de la Libération, F33405 Talence, France
| | - Dominique Descamps
- CELIA, Université de Bordeaux - CNRS - CEA, UMR5107, 351 Cours de la Libération, F33405 Talence, France
| | - Stéphane Petit
- CELIA, Université de Bordeaux - CNRS - CEA, UMR5107, 351 Cours de la Libération, F33405 Talence, France
| | - Valérie Blanchet
- CELIA, Université de Bordeaux - CNRS - CEA, UMR5107, 351 Cours de la Libération, F33405 Talence, France
| | - Jérôme Gaudin
- CELIA, Université de Bordeaux - CNRS - CEA, UMR5107, 351 Cours de la Libération, F33405 Talence, France
| | - Yann Mairesse
- CELIA, Université de Bordeaux - CNRS - CEA, UMR5107, 351 Cours de la Libération, F33405 Talence, France
| | - Bernard Marty
- Centre de Recherches Pétrographiques et Géochimiques, UMR 7358 CNRS - Université de Lorraine, 15 rue Notre Dame des Pauvres, BP 20, F-54501 Vandoeuvre-lès-Nancy, France
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26
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He C, Yang Z, Doddipatla S, Zhao L, Goettl S, Kaiser RI, Silva MX, Galvão BRL. Non-Adiabatic Reaction Dynamics in the Gas-Phase Formation of Phosphinidenesilylene, the Isovalent Counterpart of Hydrogen Isocyanide, under Single-Collision Conditions. J Phys Chem Lett 2021; 12:2489-2495. [PMID: 33666441 DOI: 10.1021/acs.jpclett.1c00085] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The phosphinidenesilylene (HPSi; X1A') molecule was prepared via a directed gas-phase synthesis in the bimolecular reaction of ground-state atomic silicon (Si; 3P) with phosphine (PH3; X1A1) under single-collision conditions. The chemical dynamics are initiated on the triplet surface via addition of a silicon atom to the non-bonding electron pair of phosphine, followed by non-adiabatic dynamics and surface hopping to the singlet manifold, accompanied by isomerization via atomic hydrogen shift and decomposition to phosphinidenesilylene (HPSi, X1A') along with molecular hydrogen. Statistical calculations predict that silylidynephosphine (HSiP, X1Σ+) is also formed, albeit with lower yields. The barrier-less route to phosphinidenesilylene opens up a multipurpose mechanism to access the hitherto obscure class of phosphasilenylidenes through silicon-phosphorus coupling via reactions of atomic silicon with alkylphosphines under single-collision conditions in the absence of successive reactions of the reaction products, which are not feasible to prepare by traditional synthetic routes.
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Affiliation(s)
- Chao He
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
| | - Zhenghai Yang
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
| | - Srinivas Doddipatla
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
| | - Long Zhao
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
| | - Shane Goettl
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
| | - Mateus Xavier Silva
- Centro Federal de Educação Tecnológica de Minas Gerais, CEFET-MG, Av. Amazonas 5253, 30421-169 Belo Horizonte, Minas Gerais, Brazil
| | - Breno R L Galvão
- Centro Federal de Educação Tecnológica de Minas Gerais, CEFET-MG, Av. Amazonas 5253, 30421-169 Belo Horizonte, Minas Gerais, Brazil
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27
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Yang Z, Doddipatla S, Kaiser RI, Krasnoukhov VS, Azyazov VN, Mebel AM. Directed Gas Phase Formation of the Elusive Silylgermylidyne Radical (H 3 SiGe, X 2 A''). Chemphyschem 2021; 22:184-191. [PMID: 33245830 DOI: 10.1002/cphc.202000913] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 11/25/2020] [Indexed: 11/11/2022]
Abstract
The previously unknown silylgermylidyne radical (H3 SiGe; X2 A'') was prepared via the bimolecular gas phase reaction of ground state silylidyne radicals (SiH; X2 Π) with germane (GeH4 ; X1 A1 ) under single collision conditions in crossed molecular beams experiments. This reaction begins with the formation of a van der Waals complex followed by insertion of silylidyne into a germanium-hydrogen bond forming the germylsilyl radical (H3 GeSiH2 ). A hydrogen migration isomerizes this intermediate to the silylgermyl radical (H2 GeSiH3 ), which undergoes a hydrogen shift to an exotic, hydrogen-bridged germylidynesilane intermediate (H3 Si(μ-H)GeH); this species emits molecular hydrogen forming the silylgermylidyne radical (H3 SiGe). Our study offers a remarkable glance at the complex reaction dynamics and inherent isomerization processes of the silicon-germanium system, which are quite distinct from those of the isovalent hydrocarbon system (ethyl radical; C2 H5 ) eventually affording detailed insights into an exotic chemistry and intriguing chemical bonding of silicon-germanium species at the microscopic level exploiting crossed molecular beams.
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Affiliation(s)
- Zhenghai Yang
- Department of Chemistry, University of Hawaii, Honolulu, HI, 96822, USA
| | | | - Ralf I Kaiser
- Department of Chemistry, University of Hawaii, Honolulu, HI, 96822, USA
| | - Vladislav S Krasnoukhov
- Samara National Research University, Samara 443086 and Lebedev Physical Institute, Samara, 443011, Russian Federation
| | - Valeriy N Azyazov
- Samara National Research University, Samara 443086 and Lebedev Physical Institute, Samara, 443011, Russian Federation
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
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28
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He C, Nikolayev AA, Zhao L, Thomas AM, Doddipatla S, Galimova GR, Azyazov VN, Mebel AM, Kaiser RI. Gas-Phase Formation of C 5H 6 Isomers via the Crossed Molecular Beam Reaction of the Methylidyne Radical (CH; X 2Π) with 1,2-Butadiene (CH 3CHCCH 2; X 1A'). J Phys Chem A 2021; 125:126-138. [PMID: 33397109 DOI: 10.1021/acs.jpca.0c08731] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The bimolecular gas-phase reaction of the methylidyne radical (CH; X2Π) with 1,2-butadiene (CH2CCHCH3; X1A') was investigated at a collision energy of 20.6 kJ mol-1 under single collision conditions. Combining our laboratory data with high-level electronic structure calculations, we reveal that this bimolecular reaction proceeds through the barrierless addition of the methylidyne radical to the carbon-carbon double bonds of 1,2-butadiene leading to doublet C5H7 intermediates. These collision adducts undergo a nonstatistical unimolecular decomposition through atomic hydrogen elimination to at least the cyclic 1-vinyl-cyclopropene (p5/p26), 1-methyl-3-methylenecyclopropene (p28), and 1,2-bis(methylene)cyclopropane (p29) in overall exoergic reactions. The barrierless nature of this bimolecular reaction suggests that these cyclic C5H6 isomers might be viable targets to be searched for in cold molecular clouds like TMC-1.
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Affiliation(s)
- Chao He
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
| | | | - Long Zhao
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
| | - Aaron M Thomas
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
| | - Srinivas Doddipatla
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
| | - Galiya R Galimova
- Samara National Research University, Samara 443086, Russian Federation.,Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
| | - Valeriy N Azyazov
- Samara National Research University, Samara 443086, Russian Federation.,Lebedev Physical Institute, Samara 443011, Russian Federation
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
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29
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Doddipatla S, Galimova GR, Wei H, Thomas AM, He C, Yang Z, Morozov AN, Shingledecker CN, Mebel AM, Kaiser RI. Low-temperature gas-phase formation of indene in the interstellar medium. SCIENCE ADVANCES 2021; 7:7/1/eabd4044. [PMID: 33523847 PMCID: PMC7775774 DOI: 10.1126/sciadv.abd4044] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 11/04/2020] [Indexed: 06/07/2023]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are fundamental molecular building blocks of fullerenes and carbonaceous nanostructures in the interstellar medium and in combustion systems. However, an understanding of the formation of aromatic molecules carrying five-membered rings-the essential building block of nonplanar PAHs-is still in its infancy. Exploiting crossed molecular beam experiments augmented by electronic structure calculations and astrochemical modeling, we reveal an unusual pathway leading to the formation of indene (C9H8)-the prototype aromatic molecule with a five-membered ring-via a barrierless bimolecular reaction involving the simplest organic radical-methylidyne (CH)-and styrene (C6H5C2H3) through the hitherto elusive methylidyne addition-cyclization-aromatization (MACA) mechanism. Through extensive structural reorganization of the carbon backbone, the incorporation of a five-membered ring may eventually lead to three-dimensional PAHs such as corannulene (C20H10) along with fullerenes (C60, C70), thus offering a new concept on the low-temperature chemistry of carbon in our galaxy.
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Affiliation(s)
- Srinivas Doddipatla
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA
| | - Galiya R Galimova
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL, 33199, USA
- Samara National Research University, Samara 443086, Russia
| | - Hongji Wei
- Department of Physics and Astronomy, Benedictine College, Atchison, KS 66002, USA
| | - Aaron M Thomas
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA
| | - Chao He
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA
| | - Zhenghai Yang
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA
| | - Alexander N Morozov
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL, 33199, USA
| | | | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL, 33199, USA.
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA.
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30
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He C, Galimova GR, Luo Y, Zhao L, Eckhardt AK, Sun R, Mebel AM, Kaiser RI. A chemical dynamics study on the gas-phase formation of triplet and singlet C 5H 2 carbenes. Proc Natl Acad Sci U S A 2020; 117:30142-30150. [PMID: 33199606 PMCID: PMC7720239 DOI: 10.1073/pnas.2019257117] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Since the postulation of carbenes by Buchner (1903) and Staudinger (1912) as electron-deficient transient species carrying a divalent carbon atom, carbenes have emerged as key reactive intermediates in organic synthesis and in molecular mass growth processes leading eventually to carbonaceous nanostructures in the interstellar medium and in combustion systems. Contemplating the short lifetimes of these transient molecules and their tendency for dimerization, free carbenes represent one of the foremost obscured classes of organic reactive intermediates. Here, we afford an exceptional glance into the fundamentally unknown gas-phase chemistry of preparing two prototype carbenes with distinct multiplicities-triplet pentadiynylidene (HCCCCCH) and singlet ethynylcyclopropenylidene (c-C5H2) carbene-via the elementary reaction of the simplest organic radical-methylidyne (CH)-with diacetylene (HCCCCH) under single-collision conditions. Our combination of crossed molecular beam data with electronic structure calculations and quasi-classical trajectory simulations reveals fundamental reaction mechanisms and facilitates an intimate understanding of bond-breaking processes and isomerization processes of highly reactive hydrocarbon intermediates. The agreement between experimental chemical dynamics studies under single-collision conditions and the outcome of trajectory simulations discloses that molecular beam studies merged with dynamics simulations have advanced to such a level that polyatomic reactions with relevance to extreme astrochemical and combustion chemistry conditions can be elucidated at the molecular level and expanded to higher-order homolog carbenes such as butadiynylcyclopropenylidene and triplet heptatriynylidene, thus offering a versatile strategy to explore the exotic chemistry of novel higher-order carbenes in the gas phase.
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Affiliation(s)
- Chao He
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, HI 96822
| | - Galiya R Galimova
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199
- Laboratory of Combustion Physics and Chemistry, Samara National Research University, Samara 443086, Russia
| | - Yuheng Luo
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, HI 96822
| | - Long Zhao
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, HI 96822
| | - André K Eckhardt
- Institute of Organic Chemistry, Justus Liebig University, 35392 Giessen, Germany
| | - Rui Sun
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, HI 96822;
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199;
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, HI 96822;
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31
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Varakin V. Photolysis of adsorbed polyatomic molecules on dielectric surfaces: General mechanisms. J Photochem Photobiol A Chem 2020. [DOI: 10.1016/j.jphotochem.2020.112850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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32
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He C, Zhao L, Doddipatla S, Thomas AM, Nikolayev AA, Galimova GR, Azyazov VN, Mebel AM, Kaiser RI. Gas-Phase Synthesis of 3-Vinylcyclopropene via the Crossed Beam Reaction of the Methylidyne Radical (CH; X 2 Π) with 1,3-Butadiene (CH 2 CHCHCH 2 ; X 1 A g ). Chemphyschem 2020; 21:1295-1309. [PMID: 32291897 DOI: 10.1002/cphc.202000183] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 04/12/2020] [Indexed: 12/18/2022]
Abstract
The crossed molecular beam reactions of the methylidyne radical (CH; X2 Π) with 1,3-butadiene (CH2 CHCHCH2 ; X1 Ag ) along with their (partially) deuterated counterparts were performed at collision energies of 20.8 kJ mol-1 under single collision conditions. Combining our laboratory data with ab initio calculations, we reveal that the methylidyne radical may add barrierlessly to the terminal carbon atom and/or carbon-carbon double bond of 1,3-butadiene, leading to doublet C5 H7 intermediates with life times longer than the rotation periods. These collision complexes undergo non-statistical unimolecular decomposition through hydrogen atom emission yielding the cyclic cis- and trans-3-vinyl-cyclopropene products with reaction exoergicities of 119±42 kJ mol-1 . Since this reaction is barrierless, exoergic, and all transition states are located below the energy of the separated reactants, these cyclic C5 H6 products are predicted to be accessed even in low-temperature environments, such as in hydrocarbon-rich atmospheres of planets and cold molecular clouds such as TMC-1.
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Affiliation(s)
- Chao He
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii, 96822, USA
| | - Long Zhao
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii, 96822, USA
| | - Srinivas Doddipatla
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii, 96822, USA
| | - Aaron M Thomas
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii, 96822, USA
| | | | - Galiya R Galimova
- Samara National Research University, Samara, 443086, Russian Federation.,Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, 33199, USA
| | - Valeriy N Azyazov
- Samara National Research University, Samara, 443086, Russian Federation.,Lebedev Physical Institute, Samara, 443011, Russian Federation
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, 33199, USA
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii, 96822, USA
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33
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Murga MS, Wiebe DS, Vasyunin AI, Varakin VN, Stolyarov AV. Experimental and theoretical studies of photoinduced reactions in the solid phase of the interstellar medium. RUSSIAN CHEMICAL REVIEWS 2020. [DOI: 10.1070/rcr4912] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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34
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He C, Thomas AM, Galimova GR, Mebel AM, Kaiser RI. Gas-Phase Formation of 1-Methylcyclopropene and 3-Methylcyclopropene via the Reaction of the Methylidyne Radical (CH; X 2Π) with Propylene (CH 3CHCH 2; X 1A'). J Phys Chem A 2019; 123:10543-10555. [PMID: 31718184 DOI: 10.1021/acs.jpca.9b09815] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The crossed molecular beam reactions of the methylidyne radical (CH; X2Π) with propylene (CH3CHCH2; X1A') along with (partially) substituted reactants were conducted at collision energies of 19.3 kJ mol-1. Combining our experimental data with ab initio electronic structure and statistical calculations, the methylidyne radical is revealed to add barrierlessly to the carbon-carbon double bond of propylene reactant resulting in a cyclic doublet C4H7 intermediate with a lifetime longer than its rotation period. These adducts undergo a nonstatistical unimolecular decomposition via atomic hydrogen loss through tight exit transition states forming the cyclic products 1-methylcyclopropene and 3-methylcyclopropene with overall reaction exoergicities of 168 ± 25 kJ mol-1. These C4H6 isomers are predicted to exist even in low-temperature environments such as cold molecular clouds like TMC-1, since the reaction is barrierless and exoergic, all transition states are below the energy of the separated reactants, and both the methylidyne radical (CH; X2Π) and propylene reactant were detected in cold molecular clouds such as TMC-1.
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Affiliation(s)
- Chao He
- Department of Chemistry , University of Hawai'i at Manoa , Honolulu , Hawaii 96822 , United States
| | - Aaron M Thomas
- Department of Chemistry , University of Hawai'i at Manoa , Honolulu , Hawaii 96822 , United States
| | - Galiya R Galimova
- Department of Chemistry and Biochemistry , Florida International University , Miami , Florida 33199 , United States.,Samara National Research University , Samara 443086 , Russia
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry , Florida International University , Miami , Florida 33199 , United States
| | - Ralf I Kaiser
- Department of Chemistry , University of Hawai'i at Manoa , Honolulu , Hawaii 96822 , United States
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35
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A Barrierless Pathway Accessing the C 9H 9 and C 9H 8 Potential Energy Surfaces via the Elementary Reaction of Benzene with 1-Propynyl. Sci Rep 2019; 9:17595. [PMID: 31772216 PMCID: PMC6879741 DOI: 10.1038/s41598-019-53987-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 11/07/2019] [Indexed: 11/16/2022] Open
Abstract
The crossed molecular beams reactions of the 1-propynyl radical (CH3CC; X2A1) with benzene (C6H6; X1A1g) and D6-benzene (C6D6; X1A1g) were conducted to explore the formation of C9H8 isomers under single-collision conditions. The underlying reaction mechanisms were unravelled through the combination of the experimental data with electronic structure and statistical RRKM calculations. These data suggest the formation of 1-phenyl-1-propyne (C6H5CCCH3) via the barrierless addition of 1-propynyl to benzene forming a low-lying doublet C9H9 intermediate that dissociates by hydrogen atom emission via a tight transition state. In accordance with our experiments, RRKM calculations predict that the thermodynamically most stable isomer – the polycyclic aromatic hydrocarbon (PAH) indene – is not formed via this reaction. With all barriers lying below the energy of the reactants, this reaction is viable in the cold interstellar medium where several methyl-substituted molecules have been detected. Its underlying mechanism therefore advances our understanding of how methyl-substituted hydrocarbons can be formed under extreme conditions such as those found in the molecular cloud TMC-1. Implications for the chemistry of the 1-propynyl radical in astrophysical environments are also discussed.
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36
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He C, Zhao L, Thomas AM, Galimova GR, Mebel AM, Kaiser RI. A combined experimental and computational study on the reaction dynamics of the 1-propynyl radical (CH 3CC; X 2A 1) with ethylene (H 2CCH 2; X 1A 1g) and the formation of 1-penten-3-yne (CH 2CHCCCH 3; X 1A'). Phys Chem Chem Phys 2019; 21:22308-22319. [PMID: 31576858 DOI: 10.1039/c9cp04073k] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The crossed molecular beam reactions of the 1-propynyl radical (CH3CC; X2A1) with ethylene (H2CCH2; X1A1g) and ethylene-d4 (D2CCD2; X1A1g) were performed at collision energies of 31 kJ mol-1 under single collision conditions. Combining our laboratory data with ab initio electronic structure and statistical Rice-Ramsperger-Kassel-Marcus (RRKM) calculations, we reveal that the reaction is initiated by the barrierless addition of the 1-propynyl radical to the π-electron density of the unsaturated hydrocarbon of ethylene leading to a doublet C5H7 intermediate(s) with a life time(s) longer than the rotation period(s). The reaction eventually produces 1-penten-3-yne (p1) plus a hydrogen atom with an overall reaction exoergicity of 111 ± 16 kJ mol-1. About 35% of p1 originates from the initial collision complex followed by C-H bond rupture via a tight exit transition state located 22 kJ mol-1 above the separated products. The collision complex (i1) can also undergo a [1,2] hydrogen atom shift to the CH3CHCCCH3 intermediate (i2) prior to a hydrogen atom release; RRKM calculations suggest that this pathway contributes to about 65% of p1. In higher density environments such as in combustion flames and circumstellar envelopes of carbon stars close to the central star, 1-penten-3-yne (p1) may eventually form the cyclopentadiene (c-C5H6) isomer via hydrogen atom assisted isomerization followed by hydrogen abstraction to the cyclopentadienyl radical (c-C5H5) as an important pathway to key precursors to polycyclic aromatic hydrocarbons (PAHs) and to carbonaceous nanoparticles.
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Affiliation(s)
- Chao He
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, USA.
| | - Long Zhao
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, USA.
| | - Aaron M Thomas
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, USA.
| | - Galiya R Galimova
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA. and Samara National Research University, Samara 443086, Russia
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA. and Samara National Research University, Samara 443086, Russia
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, USA.
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37
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Thomas AM, Zhao L, He C, Galimova GR, Mebel AM, Kaiser RI. Directed Gas‐Phase Synthesis of Triafulvene under Single‐Collision Conditions. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201908039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Aaron M. Thomas
- Department of Chemistry University of Hawai'i at Manoa Honolulu HI 96822 USA
| | - Long Zhao
- Department of Chemistry University of Hawai'i at Manoa Honolulu HI 96822 USA
| | - Chao He
- Department of Chemistry University of Hawai'i at Manoa Honolulu HI 96822 USA
| | - Galiya R. Galimova
- Department of Chemistry and Biochemistry Florida International University Miami FL 33199 USA
- Samara National Research University Samara 443086 Russia
| | - Alexander M. Mebel
- Department of Chemistry and Biochemistry Florida International University Miami FL 33199 USA
| | - Ralf I. Kaiser
- Department of Chemistry University of Hawai'i at Manoa Honolulu HI 96822 USA
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Thomas AM, Zhao L, He C, Galimova GR, Mebel AM, Kaiser RI. Directed Gas-Phase Synthesis of Triafulvene under Single-Collision Conditions. Angew Chem Int Ed Engl 2019; 58:15488-15495. [PMID: 31368202 DOI: 10.1002/anie.201908039] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Indexed: 11/09/2022]
Abstract
The triafulvene molecule (c-C4 H4 )-the simplest representative of the fulvene family-has been synthesized for the first time in the gas phase through the reaction of the methylidyne radical (CH) with methylacetylene (CH3 CCH) and allene (H2 CCCH2 ) under single-collision conditions. The experimental and computational data suggest triafulvene is formed by the barrierless cycloaddition of the methylidyne radical to the π-electron density of either C3 H4 isomer followed by unimolecular decomposition through elimination of atomic hydrogen from the CH3 or CH2 groups of the reactants. The dipole moment of triafulvene of 1.90 D suggests that this molecule could represent a critical tracer of microwave-inactive allene in cold molecular clouds, thus defining constraints on the largely elusive hydrocarbon chemistry in low-temperature interstellar environments, such as that of the Taurus Molecular Cloud 1 (TMC-1).
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Affiliation(s)
- Aaron M Thomas
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, HI, 96822, USA
| | - Long Zhao
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, HI, 96822, USA
| | - Chao He
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, HI, 96822, USA
| | - Galiya R Galimova
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL, 33199, USA.,Samara National Research University, Samara, 443086, Russia
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL, 33199, USA
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, HI, 96822, USA
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He C, Zhao L, Thomas AM, Morozov AN, Mebel AM, Kaiser RI. Elucidating the Chemical Dynamics of the Elementary Reactions of the 1-Propynyl Radical (CH3CC; X2A1) with Methylacetylene (H3CCCH; X1A1) and Allene (H2CCCH2; X1A1). J Phys Chem A 2019; 123:5446-5462. [DOI: 10.1021/acs.jpca.9b03746] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Chao He
- Department of Chemistry, University of Hawai’i at Manoa, Honolulu, Hawaii 96822, United States
| | - Long Zhao
- Department of Chemistry, University of Hawai’i at Manoa, Honolulu, Hawaii 96822, United States
| | - Aaron M. Thomas
- Department of Chemistry, University of Hawai’i at Manoa, Honolulu, Hawaii 96822, United States
| | - Alexander N. Morozov
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
| | - Alexander M. Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
| | - Ralf I. Kaiser
- Department of Chemistry, University of Hawai’i at Manoa, Honolulu, Hawaii 96822, United States
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Thomas AM, He C, Zhao L, Galimova GR, Mebel AM, Kaiser RI. Combined Experimental and Computational Study on the Reaction Dynamics of the 1-Propynyl (CH 3CC)-1,3-Butadiene (CH 2CHCHCH 2) System and the Formation of Toluene under Single Collision Conditions. J Phys Chem A 2019; 123:4104-4118. [PMID: 31017790 DOI: 10.1021/acs.jpca.9b00092] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The crossed beams reactions of the 1-propynyl radical (CH3CC; X2A1) with 1,3-butadiene (CH2CHCHCH2; X1Ag), 1,3-butadiene- d6 (CD2CDCDCD2; X1Ag), 1,3-butadiene- d4 (CD2CHCHCD2; X1Ag), and 1,3-butadiene- d2 (CH2CDCDCH2; X1Ag) were performed under single collision conditions at collision energies of about 40 kJ mol-1. The underlying reaction mechanisms were unraveled through the combination of the experimental data with electronic structure calculations at the CCSD(T)-F12/cc-pVTZ-f12//B3LYP/6-311G(d,p) + ZPE(B3LYP/6-311G(d,p) level of theory along with statistical Rice-Ramsperger-Kassel-Marcus (RRKM) calculations. Together, these data suggest the formation of the thermodynamically most stable C7H8 isomer-toluene (C6H5CH3)-via the barrierless addition of 1-propynyl to the 1,3-butadiene terminal carbon atom, forming a low-lying C7H9 intermediate that undergoes multiple isomerization steps resulting in cyclization and ultimately aromatization following hydrogen atom elimination. RRKM calculations predict that the thermodynamically less stable isomers 1,3-heptadien-5-yne, 5-methylene-1,3-cyclohexadiene, and 3-methylene-1-hexen-4-yne are also synthesized. Since the 1-propynyl radical may be present in cold molecular clouds such as TMC-1, this pathway could potentially serve as a carrier of the methyl group incorporating itself into methyl-substituted (poly)acetylenes or aromatic systems such as toluene via overall exoergic reaction mechanisms that are uninhibited by an entrance barrier. Such pathways are a necessary alternative to existing high energy reactions leading to toluene that are formally closed in the cold regions of space and are an important step toward understanding the synthesis of polycyclic aromatic hydrocarbons (PAHs) in space's harsh extremes.
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Affiliation(s)
- Aaron M Thomas
- Department of Chemistry , University of Hawai'i at Manoa , Honolulu , Hawaii 96822 , United States
| | - Chao He
- Department of Chemistry , University of Hawai'i at Manoa , Honolulu , Hawaii 96822 , United States
| | - Long Zhao
- Department of Chemistry , University of Hawai'i at Manoa , Honolulu , Hawaii 96822 , United States
| | - Galiya R Galimova
- Department of Chemistry and Biochemistry , Florida International University , Miami , Florida 33199 , United States.,Samara National Research University , Samara 443086 , Russia
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry , Florida International University , Miami , Florida 33199 , United States
| | - Ralf I Kaiser
- Department of Chemistry , University of Hawai'i at Manoa , Honolulu , Hawaii 96822 , United States
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Thomas AM, Zhao L, He C, Mebel AM, Kaiser RI. A Combined Experimental and Computational Study on the Reaction Dynamics of the 1-Propynyl (CH3CC)–Acetylene (HCCH) System and the Formation of Methyldiacetylene (CH3CCCCH). J Phys Chem A 2018; 122:6663-6672. [DOI: 10.1021/acs.jpca.8b05530] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Aaron M. Thomas
- Department of Chemistry, University of Hawai’i at Manoa, Honolulu, Hawaii 96822, United States
| | - Long Zhao
- Department of Chemistry, University of Hawai’i at Manoa, Honolulu, Hawaii 96822, United States
| | - Chao He
- Department of Chemistry, University of Hawai’i at Manoa, Honolulu, Hawaii 96822, United States
| | - Alexander M. Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
| | - Ralf I. Kaiser
- Department of Chemistry, University of Hawai’i at Manoa, Honolulu, Hawaii 96822, United States
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Thomas AM, Lucas M, Zhao L, Liddiard J, Kaiser RI, Mebel AM. A combined crossed molecular beams and computational study on the formation of distinct resonantly stabilized C 5H 3 radicals via chemically activated C 5H 4 and C 6H 6 intermediates. Phys Chem Chem Phys 2018. [PMID: 29537029 DOI: 10.1039/c8cp00357b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The crossed molecular beams technique was utilized to explore the formation of three isomers of resonantly stabilized (C5H3) radicals along with their d2-substituted counterparts via the bimolecular reactions of singlet/triplet dicarbon [C2(X1Σ+g/a3Πu)] with methylacetylene [CH3CCH(X1A1)], d3-methylacetylene [CD3CCH(X1A1)], and 1-butyne [C2H5CCH(X1A')] at collision energies up to 26 kJ mol-1via chemically activated singlet/triplet C5H4/C5D3H and C6H6 intermediates. These studies exploit a newly developed supersonic dicarbon [C2(X1Σ+g/a3Πu)] beam generated via photolysis of tetrachloroethylene [C2Cl4(X1Ag)] by excluding interference from carbon atoms, which represent the dominating (interfering) species in ablation-based dicarbon sources. We evaluated the performance of the dicarbon [C2(X1Σ+g/a3Πu)] beam in reactions with methylacetylene [CH3CCH(X1A1)] and d3-methylacetylene [CD3CCH(X1A1)]; the investigations demonstrate that the reaction dynamics match previous studies in our laboratory utilizing ablation-based dicarbon sources involving the synthesis of 1,4-pentadiynyl-3 [HCCCHCCH(X2B1)] and 2,4-pentadiynyl-1 [H2CCCCCH(X2B1)] radicals via hydrogen (deuterium) atom elimination. Considering the C2(X1Σ+g/a3Πu)-1-butyne [C2H5CCH(X1A')] reaction, the hitherto elusive methyl-loss pathway was detected. This channel forms the previously unknown resonantly stabilized penta-1-yn-3,4-dienyl-1 [H2CCCHCC(X2A)] radical along with the methyl radical [CH3(X2A2'')] and is open exclusively on the triplet surface with an overall reaction energy of -86 ± 10 kJ mol-1. The preferred reaction pathways proceed first by barrierless addition of triplet dicarbon to the π-electronic system of 1-butyne, either to both acetylenic carbon atoms or to the sterically more accessible carbon atom, to form the methyl-bearing triplet C6H6 intermediates [i41b] and [i81b], respectively, with the latter decomposing via a tight exit transition state to penta-1-yn-3,4-dienyl-1 [(H2CCCHCC(X2A)] plus the methyl radical [CH3(X2A2'')]. The successful unraveling of this methyl-loss channel - through collaborative experimental and computational efforts - underscores the viability of the photolytically generated dicarbon beam as an unprecedented tool to access reaction dynamics underlying the formation of resonantly stabilized free radicals (RSFR) that are vital to molecular mass growth processes that ultimately lead to polycyclic aromatic hydrocarbons (PAHs).
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Affiliation(s)
- Aaron M Thomas
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA.
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Varakin V. Photolysis of adsorbed benzene at 248 nm. J Photochem Photobiol A Chem 2018. [DOI: 10.1016/j.jphotochem.2017.12.045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Lucas M, Thomas AM, Kaiser RI, Bashkirov EK, Azyazov VN, Mebel AM. Combined Experimental and Computational Investigation of the Elementary Reaction of Ground State Atomic Carbon (C; 3Pj) with Pyridine (C5H5N; X1A1) via Ring Expansion and Ring Degradation Pathways. J Phys Chem A 2018. [DOI: 10.1021/acs.jpca.8b00756] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Michael Lucas
- Department of Chemistry, University of Hawai’i at Manoa, Honolulu, Hawaii 96822, United States
| | - Aaron M. Thomas
- Department of Chemistry, University of Hawai’i at Manoa, Honolulu, Hawaii 96822, United States
| | - Ralf I. Kaiser
- Department of Chemistry, University of Hawai’i at Manoa, Honolulu, Hawaii 96822, United States
| | | | | | - Alexander M. Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
- Samara University, Samara, 443086, Russia
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Yang T, Thomas AM, Dangi BB, Kaiser RI, Mebel AM, Millar TJ. Directed gas phase formation of silicon dioxide and implications for the formation of interstellar silicates. Nat Commun 2018; 9:774. [PMID: 29472549 PMCID: PMC5823853 DOI: 10.1038/s41467-018-03172-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 01/24/2018] [Indexed: 11/12/2022] Open
Abstract
Interstellar silicates play a key role in star formation and in the origin of solar systems, but their synthetic routes have remained largely elusive so far. Here we demonstrate in a combined crossed molecular beam and computational study that silicon dioxide (SiO2) along with silicon monoxide (SiO) can be synthesized via the reaction of the silylidyne radical (SiH) with molecular oxygen (O2) under single collision conditions. This mechanism may provide a low-temperature path-in addition to high-temperature routes to silicon oxides in circumstellar envelopes-possibly enabling the formation and growth of silicates in the interstellar medium necessary to offset the fast silicate destruction.
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Affiliation(s)
- Tao Yang
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI, 96822, USA
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200062, China
| | - Aaron M Thomas
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI, 96822, USA
| | - Beni B Dangi
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI, 96822, USA
- Department of Chemistry, Florida Agricultural and Mechanical University, Tallahassee, FL, 32307, USA
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI, 96822, USA.
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL, 33199, USA.
| | - Tom J Millar
- Astrophysics Research Centre, School of Mathematics and Physics, Queen's University Belfast, Belfast, BT7 1NN, UK.
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Li Q, Yao L, Lin SH. Calculation of anharmonic effect on the dissociation of ethylene glycol. JOURNAL OF THEORETICAL & COMPUTATIONAL CHEMISTRY 2017. [DOI: 10.1142/s0219633617500778] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The unimolecular dissociation rate constants of ethylene glycol were examined using the MP2/6-311[Formula: see text]G(d,p) method based on the Rice–Ramsperger–Kassel–Marcus (RRKM) theory. The effect of anharmonicity on the dissociation rate constants was evaluated at 500–4000[Formula: see text]K temperatures of the canonical system and 25,182–50,235[Formula: see text]cm[Formula: see text] total energies of the microcanonical system. The comparison of the results showed that the H2O elimination reaction played a critical role in the decomposition processes of ethylene glycol. The results of the rate constant calculations indicated that the H2O elimination reaction dominated at low temperatures, whereas the direct C–C bond dissociation reaction (CH2OHCH2OH [Formula: see text] CH2OH[Formula: see text][Formula: see text][Formula: see text]CH2OH) dominated at high temperatures. For channel 1, CH2OH[Formula: see text][Formula: see text][Formula: see text]CH2OH, the anharmonic effect of the canonical system was not observed, while it became more obvious with the increasing total energies in the microcanonical system. For channels 2–5, CH3CHO[Formula: see text][Formula: see text][Formula: see text]H2O, CH2CHOH[Formula: see text][Formula: see text][Formula: see text]H2O, CH3OH[Formula: see text][Formula: see text][Formula: see text]CHOH, and CH2OHCHO[Formula: see text][Formula: see text][Formula: see text]H2, the anharmonic effect of canonical and microcanonical systems became more obvious with increasing temperatures and total energies. The comparison showed that, for channels 1 and 4, C–C bond dissociation and the anharmonic effect of the microcanonical system were more evident, whereas the anharmonic effect of the canonical system was more predominant for channels 2 (CH3CHO[Formula: see text][Formula: see text][Formula: see text]H2O), 3 (CH2CHOH[Formula: see text][Formula: see text][Formula: see text]H2O), and 5 (CH2OHCHO[Formula: see text][Formula: see text][Formula: see text]H2).
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Affiliation(s)
- Qian Li
- School of Energy and Mechanical Engineering, Jiangxi University of Science and Technology, Nanchang 330013, P. R. China
| | - Li Yao
- School of Marine Engineering, Dalian Maritime University, Dalian 116026, P. R. China
| | - S. H. Lin
- Department of Applied Chemistry, National Chiao-Tung University, Hsin-Chu 10764, Taiwan
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Mebel AM, Landera A, Kaiser RI. Formation Mechanisms of Naphthalene and Indene: From the Interstellar Medium to Combustion Flames. J Phys Chem A 2017; 121:901-926. [DOI: 10.1021/acs.jpca.6b09735] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Alexander M. Mebel
- Department
of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
| | - Alexander Landera
- Chemical
Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Ralf I. Kaiser
- Department
of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, United States
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West NA, Winner JD, Bowersox RDW, North SW. Resolving the energy and temperature dependence of C6H6∗ collisional relaxation via time-dependent bath temperature measurements. J Chem Phys 2016; 145:014308. [DOI: 10.1063/1.4954896] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Affiliation(s)
- Niclas A. West
- Department of Chemistry, Texas A&M University, 3012 TAMU, College Station, Texas 77842, USA
| | - Joshua D. Winner
- Department of Chemistry, Texas A&M University, 3012 TAMU, College Station, Texas 77842, USA
| | - Rodney D. W. Bowersox
- Department of Aerospace Engineering, Texas A&M University, 3141 TAMU, College Station, Texas 77842, USA
| | - Simon W. North
- Department of Chemistry, Texas A&M University, 3012 TAMU, College Station, Texas 77842, USA
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Mebel AM, Kaiser RI. Formation of resonantly stabilised free radicals via the reactions of atomic carbon, dicarbon, and tricarbon with unsaturated hydrocarbons: theory and crossed molecular beams experiments. INT REV PHYS CHEM 2015. [DOI: 10.1080/0144235x.2015.1075280] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Alexander M. Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Ralf I. Kaiser
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA
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