화학공학소재연구정보센터
Journal of Physical Chemistry A, Vol.115, No.26, 7823-7833, 2011
High-Accuracy Theoretical Thermochemistry of Atmospherically Important Sulfur-Containing Molecules
In this study, several sulfur-containing molecules with atmospherical importance were investigated by means of high-accuracy quantum chemical calculations including: HSO, HOS, HOSO(2), HSNO, SH, CH(2)SO, CH(2)SH, S(2)COH, and SCSOH. After identifying the stable conformers of the molecules, a coupled-cluster-based composite model chemistry, which includes contributions up to quadruple excitations as well as corrections beyond the nonrelativistic and Born Oppenheimer approximations, was applied to calculate the corresponding heat of formation (Delta(f)H(0)(o) and Delta fH(298)(o)) and entropy (S(298)(o)) values. In most of the cases, this study delivers more reliable estimates for the investigated thermodynamic properties than those reported in previous investigations. Our data also suggest that the experimental heats of formation associated with the HSO molecule are very likely to belong to its structural isomer, HOS. It is also confirmed by the calculated thermodynamic properties including standard reaction entropies, enthalpies, and equilibrium constants that, in the reaction CS(2) + OH reversible arrow CS(2)OH, the SCSOH structural isomer is produced. It is also noted that the currently accepted Delta(f)H(0)(o)(S(gas)) = 274.73 +/- 0.3 kJ/mol value is in need of revision, and based on a recent measurement, which is also confirmed by our computations, it is advised to update it to Delta(f)H(0)(o)(S(gas)) = 277.25 +/- 0.3 kJ/mol.