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Title: A Gaussian-2 ab initio study of [C2H5S]+ ions: III. H2 and CH4 eliminations from CH3CHSH+ and CH3SCH+ 2
Authors: Chiu, S.-W.
Lau, K.-C.
Li, W.-K.
Ma, N.L. 
Cheung, Y.-S.
Ng, C.Y.
Keywords: [C2H3S]+ ions
[C2H5S]+ ions
CH4 elimination
Gaussian-2 theory
H2 elimination
Unimolecular dissociation
Issue Date: 1-Nov-1999
Source: Chiu, S.-W.,Lau, K.-C.,Li, W.-K.,Ma, N.L.,Cheung, Y.-S.,Ng, C.Y. (1999-11-01). A Gaussian-2 ab initio study of [C2H5S]+ ions: III. H2 and CH4 eliminations from CH3CHSH+ and CH3SCH+ 2. Journal of Molecular Structure: THEOCHEM 490 (1-3) : 109-124. ScholarBank@NUS Repository.
Abstract: Gaussian-2 ab initio calculations were performed to examine the six modes of unimolecular dissociation of cis-CH3CHSH+ (1+), trans-CH3CHSH+ (2+), and CH3SCH+ 2 (3+): 1+ → CH+ 3 + trans-HCSH (1); 1+ → CH3 + trans-HCSH+ (2); 1+ → CH4 + HCS+ (3); 1+ → H2 + c-CH2CHS+ (4); 2+ → H2 + CH3CS+ (5); and 3+ → H2 + c-CH2CHS+ (6). Reactions (1) and (2) have endothermicities of 584 and 496 kJ mol-1, respectively. Loss of CH4 from 1+ (reaction (3)) proceeds through proton transfer from the S atom to the methyl group, followed by cleavage of the C-C bond. The reaction pathway has an energy barrier of 292 kJ mol-1 and a transition state with a wide spectrum of nonclassical structures. Reaction (4) has a critical energy of 296 kJ mol-1 and it also proceeds through the same proton transfer step as reaction (3), followed by elimination of H2 Formation of CH3CS+ from 2+ (reaction (5)) by loss of H2 proceeds through protonation of the methine (CαH) group, followed by dissociation of the H2 moiety. Its energy barrier is 276 kJ mol-1. On both the MP2/6-31G* and QCISD/6-31G* potential-energy surfaces, the H2 1,1-elimination from 3+ (reaction (6)) proceeds via a nonclassical intermediate resembling c-CH3SCH+ 2 and has a critical energy of 269 kJ mol-1. © 1999 Elsevier Science B.V. All rights reserved.
Source Title: Journal of Molecular Structure: THEOCHEM
ISSN: 01661280
Appears in Collections:Staff Publications

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