Theoretical study of the organosulfur systems CSH[sub [ital n]] ([ital n]=0--4) and CSH[sub [ital n][sup +]] ([ital n]=0--5): Dissociation energies, ionization energies, and enthalpies of formation

Journal Article · Sat Oct 31 19:00:00 EST 1992 · Journal of Chemical Physics; (United States)

DOI:https://doi.org/10.1063/1.463654· OSTI ID:7011925

Curtiss, L A ^[1]; Nobes, R H ^[2]; Pople, J A ^[3]; Radom, L ^[4]

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1. Chemical Technology Division/Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
2. Australian National University Supercomputer Facility, Canberra, ACT 2601 (Australia)
3. Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvannia 15213 (United States)
4. Research School of Chemistry, Australian National University, Canberra, ACT 2601 (Australia)

The Gaussian-2 (G2) theoretical procedure, based on [ital ab] [ital initio] molecular orbital theory, is used to calculate the energies of the CSH[sub [ital n]] ([ital n]=0--4) hydrides and CSH[sub [ital n][sup +]] ([ital n]=0--5) cations. The G2 adiabatic ionization energies of CH[sub 3]SH, CH[sub 2]SH, CH[sub 3]S, CH[sub 2]S, HCS, and CS as well as the proton affinity of CH[sub 3]SH are all in satisfactory agreement with experimental values. G2 enthalpies of formation of the neutrals and cations have also been calculated and are used to help assess the reliability of the experimental values, which in some cases cover a rather wide range. The calculated enthalpy of formation of CH[sub 3]S at 0 K is 31.6 kcal/mol. This supports the value of 31.44 kcal/mol reported in a recent kinetics study over values of 34.2--35.5 kcal/mol obtained in recent photofragmentation studies. Theoretical S--H and C--H bond dissociation energies for CH[sub 3]SH are 86.0 and 95.0 kcal/mol, respectively. G2 theory predicts the CH[sub 2]SH[sup +] cation to lie 33.1 kcal/mol lower in energy than the CH[sub 3]S[sup +] cation, in good agreement with the value of 33.5[plus minus]2 kcal/mol obtained in a recent photoionization study, but differing significantly from results of previous experimental work that gave a much larger energy difference. The G2 enthalpies of formation at 0 K of CH[sub 2]S, CH[sub 2]S[sup +], HCS, and HCS[sup +] are calculated to be 28.7, 245.0, 70.8, and 241.7 kcal/mol, respectively.

• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 7011925
• Journal Information: Journal of Chemical Physics; (United States), Journal Name: Journal of Chemical Physics; (United States) Vol. 97:9; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

664200* -- Spectra of Atoms & Molecules & their Interactions with Photons-- (1992-)
74 ATOMIC AND MOLECULAR PHYSICS
AFFINITY
CATIONS
CHARGED PARTICLES
DISSOCIATION ENERGY
ENERGY
FORMATION FREE ENTHALPY
FREE ENTHALPY
HYDRIDES
HYDROGEN COMPOUNDS
IONIZATION POTENTIAL
IONS
MOLECULAR IONS
MOLECULAR ORBITAL METHOD
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PHYSICAL PROPERTIES
THERMODYNAMIC PROPERTIES