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Bégué D, Lafargue-Dit-Hauret W, Dargelos A, Wentrup C. CHNO - Formylnitrene, Cyanic, Isocyanic, Fulminic, and Isofulminic Acids and their Interrelationships at DFT and CASPT2 Levels of Theory. J Phys Chem A 2023; 127:9088-9097. [PMID: 37875391 DOI: 10.1021/acs.jpca.3c05805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2023]
Abstract
Fulminic and cyanic acids played a decisive role in the conception of isomerism 200 years ago. Cyanic (HOCN), isocyanic (HNCO), and fulminic (HCNO) acids have been detected in several interstellar sources, but isofulminic acid (HONC) is little known. Here we examine the interrelationships between the four acids and formylnitrene, HC(O)N, at the CASPT2 and three DFT levels. Formylnitrene has a triplet ground state, T0, a closed shell singlet (CSS), S0, and an open-shell singlet (OSS), S1, lying ∼7 and 27 kcal/mol above T0, respectively. The CSS is weakly stabilized by a 12 kcal/mol bond between the N and the O atoms. A conical intersection 12 kcal/mol above T0 permits easy T0-S0 interchange. Formyl azide and formylnitrene (T0 and S0) are isomerized thermally to HNCO. HOCN is best obtained via dissociation of the nitrene (or of HNCO) to H• + NCO• radicals ∼46 kcal/mol above the T0 nitrene. Isofulminic acid, HONC, isomerizes readily to cyanic acid, HOCN, in thermal and photochemical reactions. Fulminic acid, HCNO, can isomerize to HNCO via CSS formylnitrene. Easy tautomerization prevents the preparation of HOCN in quantity. The barrier to isomerization is strongly reduced in small hydrogen-bonded aggregates so that trace amounts of HOCN can exist in equilibrium with HNCO.
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Affiliation(s)
- Didier Bégué
- CNRS/Université de Pau et des Pays de l'Adour/E2S UPPA, Institut des Sciences Analytiques et de Physicochimie pour l'Environnement et les Matériaux, UMR5254, 64000, Pau, France
| | - William Lafargue-Dit-Hauret
- CNRS/Université de Pau et des Pays de l'Adour/E2S UPPA, Institut des Sciences Analytiques et de Physicochimie pour l'Environnement et les Matériaux, UMR5254, 64000, Pau, France
| | - Alain Dargelos
- CNRS/Université de Pau et des Pays de l'Adour/E2S UPPA, Institut des Sciences Analytiques et de Physicochimie pour l'Environnement et les Matériaux, UMR5254, 64000, Pau, France
| | - Curt Wentrup
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland 4072, Australia
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2
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Synthesis of Synthetic Musks: A Theoretical Study Based on the Relationships between Structure and Properties at Molecular Scale. Int J Mol Sci 2023; 24:ijms24032768. [PMID: 36769089 PMCID: PMC9917709 DOI: 10.3390/ijms24032768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2023] [Revised: 01/28/2023] [Accepted: 01/30/2023] [Indexed: 02/04/2023] Open
Abstract
Synthetic musks (SMs), as an indispensable odor additive, are widely used in various personal care products. However, due to their physico-chemical properties, SMs were detected in various environmental media, even in samples from arctic regions, leading to severe threats to human health (e.g., abortion risk). Environmentally friendly and functionally improved SMs have been theoretically designed in previous studies. However, the synthesizability of these derivatives has barely been proven. Thus, this study developed a method to verify the synthesizability of previously designed SM derivatives using machine learning, 2D-QSAR, 3D-QSAR, and high-throughput density functional theory in order to screen for synthesizable, high-performance (odor sensitivity), and environmentally friendly SM derivatives. In this study, three SM derivatives (i.e., D52, D37, and D25) were screened and recommended due to their good performances (i.e., high synthesizability and odor sensitivity; low abortion risk; and bioaccumulation ability in skin keratin). In addition, the synthesizability mechanism of SM derivatives was also analyzed. Results revealed that high intramolecular hydrogen bond strength, electrostatic interaction, qH+ value, energy gap, and low EHOMO would lead to a higher synthesizability of SMs and their derivatives. This study broke the synthesizability bottleneck of theoretically designed environment-friendly SM derivatives and advanced the mechanism of screening functional derivatives.
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3
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McCarthy MC, Lee KLK, Porterfield JP, Changala PB, Eckhardt AK. Carbon-13 studies of sulphur-terminated carbon chains: chemical bonding, molecular structures, and formation pathways. Mol Phys 2021. [DOI: 10.1080/00268976.2021.1975052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
| | - Kin Long Kelvin Lee
- Center for Astrophysics — Harvard & Smithsonian, Cambridge, MA, USA
- Department of Chemistry, MIT, Cambridge, MA, USA
| | | | | | - André K. Eckhardt
- Center for Astrophysics — Harvard & Smithsonian, Cambridge, MA, USA
- Department of Chemistry, MIT, Cambridge, MA, USA
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4
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Krupa J, Wierzejewska M, Lundell J. Structure and IR Spectroscopic Properties of HNCO Complexes with SO 2 Isolated in Solid Argon. Molecules 2021; 26:molecules26216441. [PMID: 34770850 PMCID: PMC8587861 DOI: 10.3390/molecules26216441] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 10/13/2021] [Accepted: 10/22/2021] [Indexed: 11/16/2022] Open
Abstract
FTIR spectroscopy was combined with the matrix isolation technique and quantum chemical calculations with the aim of studying complexes of isocyanic acid with sulfur dioxide. The structures of the HNCO⋯SO2 complexes of 1:1, 1:2 and 2:1 stoichiometry were optimized at the MP2, B3LYPD3, B2PLYPD3 levels of theory with the 6-311++G(3df,3pd) basis set. Five stable 1:1 HNCO⋯SO2 complexes were found. Three of them contain a weak N-H⋯O hydrogen bond, whereas two other structures are stabilized by van der Waals interactions. The analysis of the HNCO/SO2/Ar spectra after deposition indicates that mostly the 1:1 hydrogen-bonded complexes are present in argon matrices, with a small amount of the van der Waals structures. Upon annealing, complexes of the 1:2 stoichiometry were detected, as well.
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Affiliation(s)
- Justyna Krupa
- Faculty of Chemistry, University of Wroclaw, Joliot-Curie 14, 50-383 Wroclaw, Poland;
- Correspondence: (J.K.); (J.L.); Tel.: +358-40-744-5270 (J.L.)
| | - Maria Wierzejewska
- Faculty of Chemistry, University of Wroclaw, Joliot-Curie 14, 50-383 Wroclaw, Poland;
| | - Jan Lundell
- Department of Chemistry, University of Jyväskylä, P.O. Box 35, FI-40014 Jyväskylä, Finland
- Correspondence: (J.K.); (J.L.); Tel.: +358-40-744-5270 (J.L.)
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5
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Qian W, Lu B, Tan G, Rauhut G, Grützmacher H, Zeng X. Vibrational spectrum and photochemistry of phosphaketene HPCO. Phys Chem Chem Phys 2021; 23:19237-19243. [PMID: 34524290 DOI: 10.1039/d1cp02860j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The vibrational spectra of the simplest phosphaketene HPCO and its isotopologue DPCO in solid Ar-matrices at 12.0 K have been analyzed with the aid of the computations at the CCSD(T)-F12a/cc-pVTZ-F12 level using configuration-selective vibrational configuration interaction (VCI). In addition to the four IR fundamentals, four overtone and ten combination bands have been unambiguously identified. Furthermore, the photochemistry of HPCO in the matrix has been investigated for the first time. Upon UV-light irradiation (365 or 266 nm), CO-elimination occurs by forming the parent phosphinidene HP that can be trapped by ˙NO to yield the elusive phosphinimine-N-oxyl radical HPNO˙. In contrast, an excimer laser (193 nm) irradiation of HPCO causes additional decomposition to H˙ and ˙PCO with concomitant formation of the long-sought phosphaethyne HOCP.
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Affiliation(s)
- Weiyu Qian
- Department of Chemistry, Fudan University, 200433 Shanghai, China.
| | - Bo Lu
- Department of Chemistry, Fudan University, 200433 Shanghai, China.
| | - Gengwen Tan
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, 215123 Suzhou, China.
| | - Guntram Rauhut
- Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, Stuttgart 70569, Germany
| | | | - Xiaoqing Zeng
- Department of Chemistry, Fudan University, 200433 Shanghai, China.
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6
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McCarthy MC, McGuire BA. Aromatics and Cyclic Molecules in Molecular Clouds: A New Dimension of Interstellar Organic Chemistry. J Phys Chem A 2021; 125:3231-3243. [DOI: 10.1021/acs.jpca.1c00129] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Michael C. McCarthy
- Center for Astrophysics
- Harvard & Smithsonian, 60 Garden Street, Cambridge Massachusetts 02138, United States
| | - Brett A. McGuire
- Center for Astrophysics
- Harvard & Smithsonian, 60 Garden Street, Cambridge Massachusetts 02138, United States
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- National Radio Astronomy Observatory, Charlottesville, Virginia 22903, United States
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Abstract
The equilibrium bond lengths of 41 small molecules are calculated by Gaussian09 and ADF2013 programs. We use five different basis sets: 6-31G*, cc-pVDZ, 6-311G+(2d,p), cc-pVTZ, and cc-pVQZ, for six different methods: Hartree-Fock, MP2, MP3, CCSD, CCSD(T), and B3LYP. The reliability of each level of theory on 89 bond lengths compared with CCSD(T)/cc-pVQZ is examined in terms of the mean absolute deviation. In particular, basis set dependence of the relative reliability of the two popular methods MP2 versus B3LYP is important to computational chemists. In addition, the efficient even-tempered basis set of Slater-type orbital called et-pVQZ, available in the ADF2013 program, is tested with the popular density functional B3LYP.
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Affiliation(s)
- Delano P. Chong
- Department of Chemistry, 2036 Main Mall, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
- Department of Chemistry, 2036 Main Mall, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
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Reilly NJ, da Silva G, Wilcox CM, Ge Z, Kokkin DL, Troy TP, Nauta K, Kable SH, McCarthy MC, Schmidt TW. Interconversion of Methyltropyl and Xylyl Radicals: A Pathway Unavailable to the Benzyl–Tropyl Rearrangement. J Phys Chem A 2018; 122:1261-1269. [DOI: 10.1021/acs.jpca.7b11914] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Neil J. Reilly
- Department
of Chemistry, University of Massachusetts Boston, 100 Morrissey
Boulevard, Boston, Massachusetts 02125, United States
| | - Gabriel da Silva
- Department
of Chemical Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Callan M. Wilcox
- School
of Chemistry, UNSW Sydney, Sydney, New South Wales 2052, Australia
| | - Zijun Ge
- School
of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Damian L. Kokkin
- Department
of Chemistry, Marquette University, P.O. Box 1881, Milwaukee, Wisconsin 53201-1881, United States
| | - Tyler P. Troy
- Advanced
Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Klaas Nauta
- School
of Chemistry, UNSW Sydney, Sydney, New South Wales 2052, Australia
| | - Scott H. Kable
- School
of Chemistry, UNSW Sydney, Sydney, New South Wales 2052, Australia
| | - Michael C. McCarthy
- Harvard−Smithsonian
Center for Astrophysics and School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Timothy W. Schmidt
- School
of Chemistry, UNSW Sydney, Sydney, New South Wales 2052, Australia
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McGuire BA, Martin-Drumel MA, Thorwirth S, Brünken S, Lattanzi V, Neill JL, Spezzano S, Yu Z, Zaleski DP, Remijan AJ, Pate BH, McCarthy MC. Molecular polymorphism: microwave spectra, equilibrium structures, and an astronomical investigation of the HNCS isomeric family. Phys Chem Chem Phys 2018; 18:22693-705. [PMID: 27478937 DOI: 10.1039/c6cp03871a] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The rotational spectra of thioisocyanic acid (HNCS), and its three energetic isomers (HSCN, HCNS, and HSNC) have been observed at high spectral resolution by a combination of chirped-pulse and Fabry-Pérot Fourier-transform microwave spectroscopy between 6 and 40 GHz in a pulsed-jet discharge expansion. Two isomers, thiofulminic acid (HCNS) and isothiofulminic acid (HSNC), calculated here to be 35-37 kcal mol(-1) less stable than the ground state isomer HNCS, have been detected for the first time. Precise rotational, centrifugal distortion, and nitrogen hyperfine coupling constants have been determined for the normal and rare isotopic species of both molecules; all are in good agreement with theoretical predictions obtained at the coupled cluster level of theory. On the basis of isotopic spectroscopy, precise molecular structures have been derived for all four isomers by correcting experimental rotational constants for the effects of rotation-vibration interaction calculated theoretically. Formation and isomerization pathways have also been investigated; the high abundance of HSCN relative to ground state HNCS, and the detection of strong lines of SH using CH3CN and H2S, suggest that HSCN is preferentially produced by the radical-radical reaction HS + CN. A radio astronomical search for HSCN and its isomers has been undertaken toward the high-mass star-forming region Sgr B2(N) in the Galactic Center with the 100 m Green Bank Telescope. While we find clear evidence for HSCN, only a tentative detection of HNCS is proposed, and there is no indication of HCNS or HSNC at the same rms noise level. HSCN, and tentatively HNCS, displays clear deviations from a single-excitation temperature model, suggesting weak masing may be occurring in some transitions in this source.
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Affiliation(s)
- Brett A McGuire
- National Radio Astronomy Observatory, 520 Edgemont Rd, Charlottesville, VA 22903, USA and Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
| | | | - Sven Thorwirth
- I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany
| | - Sandra Brünken
- I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany
| | - Valerio Lattanzi
- Max-Planck Institut für Extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching, Germany
| | - Justin L Neill
- Department of Chemistry, University of Virginia, McCormick Rd., Charlottesville, VA 22904, USA
| | - Silvia Spezzano
- Max-Planck Institut für Extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching, Germany
| | | | - Daniel P Zaleski
- Department of Chemistry, University of Virginia, McCormick Rd., Charlottesville, VA 22904, USA
| | - Anthony J Remijan
- National Radio Astronomy Observatory, 520 Edgemont Rd, Charlottesville, VA 22903, USA
| | - Brooks H Pate
- Department of Chemistry, University of Virginia, McCormick Rd., Charlottesville, VA 22904, USA
| | - Michael C McCarthy
- National Radio Astronomy Observatory, 520 Edgemont Rd, Charlottesville, VA 22903, USA and School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA 02138, USA.
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10
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Affiliation(s)
- Curt Wentrup
- School of Chemistry and Molecular Biosciences The University of Queensland Brisbane Qld 4072 Australien
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11
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Wentrup C. Flash Vacuum Pyrolysis: Techniques and Reactions. Angew Chem Int Ed Engl 2017; 56:14808-14835. [PMID: 28675675 DOI: 10.1002/anie.201705118] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Indexed: 12/13/2022]
Abstract
Flash vacuum pyrolysis (FVP) had its beginnings in the 1940s and 1950s, mainly through mass spectrometric detection of pyrolytically formed free radicals. In the 1960s many organic chemists started performing FVP experiments with the purpose of isolating new and interesting compounds and understanding pyrolysis processes. Meanwhile, many different types of apparatus and techniques have been developed, and it is the purpose of this review to present the most important methods as well as a survey of typical reactions and observations that can be achieved with the various techniques. This includes preparative FVP, chemical trapping reactions, matrix isolation, and low temperature spectroscopy of reactive intermediates and unstable molecules, the use of online mass, photoelectron, microwave, and millimeterwave spectroscopies, gas-phase laser pyrolysis, pulsed pyrolysis with supersonic jet expansion, very low pressure pyrolysis for kinetic investigations, solution-spray and falling-solid FVP for involatile compounds, and pyrolysis over solid supports and reagents. Moreover, the combination of FVP with matrix isolation and photochemistry is a powerful tool for investigations of reaction mechanism.
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Affiliation(s)
- Curt Wentrup
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Qld, 4072, Australia
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Mignon P, Allouche AR, Bacchus-Montabonel MC. Theoretical study of HNCO formation from atomic nitrogen and carbon monoxide in the presence of water. Chem Phys 2017. [DOI: 10.1016/j.chemphys.2017.03.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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13
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Hinz A, Labbow R, Rennick C, Schulz A, Goicoechea JM. HPCO-A Phosphorus-Containing Analogue of Isocyanic Acid. Angew Chem Int Ed Engl 2017; 56:3911-3915. [PMID: 28252258 PMCID: PMC5396272 DOI: 10.1002/anie.201700368] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Indexed: 11/20/2022]
Abstract
We describe the isolation and spectroscopic characterization of the heavier phosphorus-containing analogue of isocyanic acid (HPCO), and its isotopologue (DPCO). This fundamental small molecule, which has been postulated to exist in interstellar space, has thus far only been observed at low gas phase concentrations or in inert gas matrices. In this report we describe its synthesis, spectroscopic properties, and reactivity in solution.
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Affiliation(s)
- Alexander Hinz
- Department of ChemistryUniversity of OxfordChemistry Research Laboratory12 Mansfield RoadOxfordOX1 3TAUK
| | - René Labbow
- Institut für ChemieUniversität RostockAlbert-Einstein-Strasse 3a18059RostockGermany
| | - Chris Rennick
- National Physics LaboratoryHampton RoadTeddington, MiddlesexTW11 0LWUK
| | - Axel Schulz
- Institut für ChemieUniversität RostockAlbert-Einstein-Strasse 3a18059RostockGermany
| | - Jose M. Goicoechea
- Department of ChemistryUniversity of OxfordChemistry Research Laboratory12 Mansfield RoadOxfordOX1 3TAUK
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14
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Hinz A, Labbow R, Rennick C, Schulz A, Goicoechea JM. HPCO-A Phosphorus-Containing Analogue of Isocyanic Acid. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201700368] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Alexander Hinz
- Department of Chemistry; University of Oxford; Chemistry Research Laboratory; 12 Mansfield Road Oxford OX1 3TA UK
| | - René Labbow
- Institut für Chemie; Universität Rostock; Albert-Einstein-Strasse 3a 18059 Rostock Germany
| | - Chris Rennick
- National Physics Laboratory; Hampton Road Teddington, Middlesex TW11 0LW UK
| | - Axel Schulz
- Institut für Chemie; Universität Rostock; Albert-Einstein-Strasse 3a 18059 Rostock Germany
| | - Jose M. Goicoechea
- Department of Chemistry; University of Oxford; Chemistry Research Laboratory; 12 Mansfield Road Oxford OX1 3TA UK
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Sexton TM, Freindorf M, Kraka E, Cremer D. A Reaction Valley Investigation of the Cycloaddition of 1,3-Dipoles with the Dipolarophiles Ethene and Acetylene: Solution of a Mechanistic Puzzle. J Phys Chem A 2016; 120:8400-8418. [DOI: 10.1021/acs.jpca.6b07975] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
| | | | - Elfi Kraka
- Computational
and Theoretical Chemistry Group (CATCO), Department of Chemistry, Southern Methodist University 3215 Daniel Ave, Dallas, Texas 75275-0314, United States
| | - Dieter Cremer
- Computational
and Theoretical Chemistry Group (CATCO), Department of Chemistry, Southern Methodist University 3215 Daniel Ave, Dallas, Texas 75275-0314, United States
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17
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Kokkin DL, Reilly NJ, Fortenberry RC, Crawford TD, McCarthy MC. Optical spectra of the silicon-terminated carbon chain radicals SiCnH (n = 3,4,5). J Chem Phys 2014; 141:044310. [PMID: 25084913 DOI: 10.1063/1.4883521] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The gas-phase optical spectra of three silicon-terminated carbon chain radicals, SiCnH (n = 3 - 5), formed in a jet-cooled discharge of silane and acetylene, have been investigated by resonant two-color two-photon ionization and laser-induced fluorescence/dispersed fluorescence. Analysis of the spectra was facilitated by calculations performed using equation-of-motion coupled cluster methods. For SiC3H and SiC5H, the observed transitions are well-described as excitations from a (2)Π ground state to a (2)Σ state, in which vibronic coupling, likely involving a higher-lying Π state with a very large predicted f-value (close to unity), is persistent. The lowest (2)Σ states of both species are characterized by a rare silicon triple bond, which was identified previously [T. C. Smith, H. Y. Li, D. J. Clouthier, C. T. Kingston, and A. J. Merer, J. Chem. Phys. 112, 3662 (2000)] in the lowest (2)Σ state of SiCH. Although a strong Π - Π transition is predicted for SiC4H, the observed spectrum near 505 nm more likely corresponds to excitation to a relatively dark Σ state which is vibronically coupled to a nearby Π state. In contrast to the chains with an odd number of carbon atoms, which exhibit relatively sharp spectral features and lifetimes in the 10-100 ns range, SiC4H shows intrinsically broadened spectral features consistent with a ∼100 fs lifetime, and a subsequent long-lived decay (>50 μs) which we ascribe to mixing with a nearby quartet state arising from the same electronic configuration. The spin-orbit coupling constants for both SiC3H and SiC5H radicals were determined to be approximately 64 cm(-1), similar to that of SiCH (69.8 cm(-1)), suggesting that the unpaired electron in these species is localized on the silicon atom. Motivated by the new optical work, the rotational spectrum of linear SiC3H was detected by cavity Fourier-transform microwave spectroscopy in the 13-34 GHz range. Each rotational transition from the [Formula: see text] ground state exhibits well-resolved Λ-doubling and hyperfine structure; the derived rotational constant of B = 2.605 GHz is in excellent agreement with our calculations.
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Affiliation(s)
- D L Kokkin
- Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA
| | - N J Reilly
- Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA
| | - R C Fortenberry
- Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, USA
| | - T D Crawford
- Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, USA
| | - M C McCarthy
- Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA
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Crabtree KN, Talipov MR, Martinez O, O'Connor GD, Khursan SL, McCarthy MC. Detection and structure of HOON: microwave spectroscopy reveals an O-O bond exceeding 1.9 Å. Science 2013; 342:1354-7. [PMID: 24337293 DOI: 10.1126/science.1244180] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Nitric oxide (NO) reacts with hydroxyl radicals (OH) in the gas phase to produce nitrous acid, HONO, but essentially nothing is known about the isomeric nitrosyl-O-hydroxide (HOON), owing to its perceived instability. We report the detection of gas-phase HOON in a supersonic molecular beam by Fourier transform microwave spectroscopy and a precise determination of its molecular structure by further spectroscopic analysis of its (2)H, (15)N, and (18)O isotopologs. HOON contains the longest O-O bond in any known molecule (1.9149 ± 0.0005 Å) and appears surprisingly stable, with an abundance roughly 3% that of HONO in our experiments.
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Affiliation(s)
- Kyle N Crabtree
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
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19
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Freindorf M, Sexton T, Kraka E, Cremer D. The mechanism of the cycloaddition reaction of 1,3-dipole molecules with acetylene: an investigation with the unified reaction valley approach. Theor Chem Acc 2013. [DOI: 10.1007/s00214-013-1423-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Lattanzi V, Thorwirth S, Gottlieb CA, McCarthy MC. Two Isomers of Protonated Isocyanic Acid: Evidence for an Ion-Molecule Pathway for HNCO ↔ HOCN Isomerization. J Phys Chem Lett 2012; 3:3420-3424. [PMID: 26290966 DOI: 10.1021/jz301520s] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Ion-molecule reactions are thought to play a crucial role in the formation of metastable isomers, but relatively few protonated intermediates beyond HNCH(+) have been characterized at high spectral resolution. We present here laboratory measurements of the rotational spectra of protonated isocyanic acid in two isomeric forms, the ground state H2NCO(+) with C2v symmetry and a low-lying bent chain HNCOH(+), guided by coupled cluster calculations of their molecular structure. Somewhat surprisingly, HNCOH(+) is found to be more abundant than H2NCO(+), even though this metastable isomer is calculated to lie approximately 15-20 kcal/mol higher in energy. In the same way that HCNH(+) serves as a key intermediate in ion-molecule reactions that form HNC via dissociative electron recombination in cold dense interstellar molecular clouds, HNCOH(+) may play an analogous role in the conversion of HNCO to HOCN.
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Affiliation(s)
- Valerio Lattanzi
- †Harvard-Smithsonian Center for Astrophysics, and School of Engineering and Applied Science, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Sven Thorwirth
- ‡I. Physikalisches Institut, Universität zu Köln, Zülpicher Strasse 77, 50937 Köln, Germany
| | - Carl A Gottlieb
- †Harvard-Smithsonian Center for Astrophysics, and School of Engineering and Applied Science, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Michael C McCarthy
- †Harvard-Smithsonian Center for Astrophysics, and School of Engineering and Applied Science, Harvard University, Cambridge, Massachusetts 02138, United States
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Vörös T, Bazsó G, Tarczay G, Pasinszki T. Matrix-isolation spectroscopic and computational study of [2C, 2N, 2S] isomers: Photochemical generation of SCNNCS and NCSNCS from NCSSCN. J Mol Struct 2012. [DOI: 10.1016/j.molstruc.2012.04.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Mladenović M. Vibrational calculation for the HOCO radical and the cis-HOCO anion. J Chem Phys 2012; 137:014306. [DOI: 10.1063/1.4732150] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Rodriguez-Betancourtt VM, Quezada-Navarro VM, Neff M, Rauhut G. Anharmonic frequencies of [F,C,N,X] isomers (X=O,S) obtained from explicitly correlated coupled-cluster calculations. Chem Phys 2011. [DOI: 10.1016/j.chemphys.2011.06.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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McCarthy MC, Gottlieb CA, Thaddeus P, Thorwirth S, Gauss J. Rotational spectra and equilibrium structures of H2SiS and Si2S. J Chem Phys 2011; 134:034306. [DOI: 10.1063/1.3510732] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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