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Elter M, Brosz M, Sucerquia D, Kuzhelev A, Kiesewetter DC, Kurth M, Dreuw A, Prisner TF, Freudenberg J, Bunz UHF, Gräter F. Breaking Strong Alkynyl-Phenyl Bonds: Poly( para-phenylene ethynylene)s under Mechanical Stress. J Am Chem Soc 2024. [PMID: 39332820 DOI: 10.1021/jacs.4c08765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/29/2024]
Abstract
Stronger chemical bonds withstand higher mechanical forces; thus, the rupture of single bonds is preferred over the rupture of double or triple bonds or aromatic rings. We investigated bond scission in poly(dialkyl-p-phenylene ethynylene)s (PPEs), a fully conjugated polymer. In a scale-bridging approach using electron-paramagnetic resonance spectroscopy and gel permeation chromatography of cryomilled samples, in combination with density functional theory calculations and coarse-grained simulations, we conclude that mechanical force cleaves the sp-sp2 bond of PPEs (bond dissociation energy as high as 600 kJ mol-1). Bond scission primarily occurs in shear bands with locally increased shear stresses. The scission occurs in the middle of the PPE chains. Breaking sp-sp2 bonds into free radicals thus is feasible but requires significant mechanical force and an efficient stress concentration.
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Affiliation(s)
- Maximilian Elter
- Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Matthias Brosz
- Heidelberg Institute for Theoretical Studies, Schloß-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany
| | - Daniel Sucerquia
- Heidelberg Institute for Theoretical Studies, Schloß-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany
| | - Andrei Kuzhelev
- Institute of Physical and Theoretical Chemistry, Goethe Universität Frankfurt, Max-von-Laue-Str. 7, 60438 Frankfurt am Main, Germany
| | - Denis C Kiesewetter
- Heidelberg Institute for Theoretical Studies, Schloß-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany
| | - Markus Kurth
- Heidelberg Institute for Theoretical Studies, Schloß-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany
- Institute for Molecular Systems Engineering and Advanced Materials (IMSEAM) and Interdisciplinary Center for Scientific Computing (IWR), Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 225, 69120 Heidelberg, Germany
| | - Andreas Dreuw
- Interdisciplinary Center for Scientific Computing, Ruprecht-Karls University, Im Neuenheimer Feld 205, 69120 Heidelberg, Germany
| | - Thomas F Prisner
- Institute of Physical and Theoretical Chemistry, Goethe Universität Frankfurt, Max-von-Laue-Str. 7, 60438 Frankfurt am Main, Germany
| | - Jan Freudenberg
- Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Uwe H F Bunz
- Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Frauke Gräter
- Heidelberg Institute for Theoretical Studies, Schloß-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany
- Institute for Molecular Systems Engineering and Advanced Materials (IMSEAM) and Interdisciplinary Center for Scientific Computing (IWR), Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 225, 69120 Heidelberg, Germany
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2
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Schatz GC, Wodtke AM, Yang X. Spiers Memorial Lecture: New directions in molecular scattering. Faraday Discuss 2024; 251:9-62. [PMID: 38764350 DOI: 10.1039/d4fd00015c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/21/2024]
Abstract
The field of molecular scattering is reviewed as it pertains to gas-gas as well as gas-surface chemical reaction dynamics. We emphasize the importance of collaboration of experiment and theory, from which new directions of research are being pursued on increasingly complex problems. We review both experimental and theoretical advances that provide the modern toolbox available to molecular-scattering studies. We distinguish between two classes of work. The first involves simple systems and uses experiment to validate theory so that from the validated theory, one may learn far more than could ever be measured in the laboratory. The second class involves problems of great complexity that would be difficult or impossible to understand without a partnership of experiment and theory. Key topics covered in this review include crossed-beams reactive scattering and scattering at extremely low energies, where quantum effects dominate. They also include scattering from surfaces, reactive scattering and kinetics at surfaces, and scattering work done at liquid surfaces. The review closes with thoughts on future promising directions of research.
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Affiliation(s)
- George C Schatz
- Dept of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
| | - Alec M Wodtke
- Institute for Physical Chemistry, Georg August University, Goettingen, Germany
- Max Planck Institute for Multidisciplinary Natural Sciences, Goettingen, Germany.
- International Center for the Advanced Studies of Energy Conversion, Georg August University, Goettingen, Germany
| | - Xueming Yang
- Dalian Institute for Chemical Physics, Chinese Academy of Sciences, Dalian, China
- Department of Chemistry, College of Science, Southern University of Science and Technology, Shenzhen, China
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3
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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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4
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Medvedkov IA, Nikolayev AA, Yang Z, Goettl SJ, Mebel AM, Kaiser RI. Elucidating the chemical dynamics of the elementary reactions of the 1-propynyl radical (CH 3CC; X 2A 1) with 2-methylpropene ((CH 3) 2CCH 2; X 1A 1). Phys Chem Chem Phys 2024; 26:6448-6457. [PMID: 38319693 DOI: 10.1039/d3cp05872g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2024]
Abstract
Exploiting the crossed molecular beam technique, we studied the reaction of the 1-propynyl radical (CH3CC; X2A1) with 2-methylpropene (isobutylene; (CH3)2CCH2; X1A1) at a collision energy of 38 ± 3 kJ mol-1. The experimental results along with ab initio and statistical calculations revealed that the reaction has no entrance barrier and proceeds via indirect scattering dynamics involving C7H11 intermediates with lifetimes longer than their rotation period(s). The reaction is initiated by the addition of the 1-propynyl radical with its radical center to the π-electron density at the C1 and/or C2 position in 2-methylpropene. Further, the C7H11 intermediate formed from the C1 addition either emits atomic hydrogen or undergoes isomerization via [1,2-H] shift from the CH3 or CH2 group prior to atomic hydrogen loss preferentially leading to 1,2,4-trimethylvinylacetylene (2-methylhex-2-en-4-yne) as the dominant product. The molecular structures of the collisional complexes promote hydrogen atom loss channels. RRKM results show that hydrogen elimination channels dominate in this reaction, with a branching ratio exceeding 70%. Since the reaction of the 1-propynyl radical with 2-methylpropene has no entrance barrier, is exoergic, and all transition states involved are located below the energy of the separated reactants, bimolecular collisions are feasible to form trimethylsubstituted 1,3-enyne (p1) via a single collision event even at temperatures as low as 10 K prevailing in cold molecular clouds such as G+0.693. The formation of trimethylsubstituted vinylacetylene could serve as the starting point of fundamental molecular mass growth processes leading to di- and trimethylsubstituted naphthalenes via the HAVA mechanism.
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Affiliation(s)
- Iakov A Medvedkov
- 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.
| | - Shane J Goettl
- 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, Florida 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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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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6
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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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7
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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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8
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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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9
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Galimova GR, Mebel AM, Goettl SJ, Yang Z, Kaiser RI. A crossed molecular beams and computational study on the unusual reactivity of banana bonds of cyclopropane (c-C 3H 6; ) through insertion by ground state carbon atoms (C( 3P j)). Phys Chem Chem Phys 2022; 24:22453-22463. [PMID: 36102937 DOI: 10.1039/d2cp03293g] [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 mechanism and chemical dynamics of the reaction of ground electronic state atomic carbon C(3Pj) with cyclopropane c-C3H6 have been explored by combining crossed molecular beams experiments with electronic structure calculations of the pertinent triplet C4H6 potential energy surface and statistical computations of product branching ratios under single-collision conditions. The experimental findings suggest that the reaction proceeds via indirect scattering dynamics through triplet C4H6 reaction intermediate(s) leading to C4H5 product(s) plus atomic hydrogen via a tight exit transition state, with the overall reaction exoergicity evaluated as 231 ± 52 kJ mol-1. The calculations indicate that C(3Pj) can easily insert into one of the three equivalent C-C 'banana' bonds of cyclopropane overcoming a low barrier of only 2 kJ mol-1 following the formation of a van der Waals reactant complex stabilized by 15 kJ mol-1. The carbon atom insertion into one of the six C-H bonds is also feasible via a slightly higher barrier of 5 kJ mol-1. These results highlight an unusual reactivity of cyclopropane's banana C-C bonds, which behave more like unsaturated C-C bonds with a π-character than saturated σ C-C bonds, which are known to be generally unreactive toward the ground electronic state atomic carbon such as in ethane (C2H6). The statistical theory predicts the overall product branching ratios at the experimental collision energy as 50% for 1-butyn-4-yl, 33% for 1,3-butadien-2-yl, i-C4H5, and 11% for 1,3-butadien-1-yl, n-C4H5, with i-C4H5 (230 kJ mol-1 below the reactants) favored by the C-C insertion providing the best match with the experimentally observed reaction exoergicity. The C(3Pj) + c-C3H6 reaction is predicted to be a source of C4H5 radicals under the conditions where its low entrance barriers can be overcome, such as in planetary atmospheres or in circumstellar envelopes but not in cold molecular clouds. Both i- and n-C4H5 can further react with acetylene eventually producing the first aromatic ring and hence, the reaction of the atomic carbon with c-C3H6 can be considered as an initial step toward the formation of benzene.
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Affiliation(s)
- Galiya R Galimova
- 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.
| | - Shane J Goettl
- 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.
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA.
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10
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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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11
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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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12
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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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13
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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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14
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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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15
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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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16
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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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17
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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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18
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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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19
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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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20
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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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21
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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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22
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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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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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