Thermochemistry of new molecular species: SBr and HSBr

Total energies, optimized geometries, and vibrational frequencies of SBr and HSBr have been evaluated at the coupled cluster level of theory with the correlation consistent basis sets. Extrapolated to the complete basis set limit and with corrections for core-valence, scalar relativistic, and spin-orbit effects, atomization energies were computed and then combined with the experimental heats of formation of the atomic species to generate very accurate heats of formation for the species SBr and HSBr. For SBr, we predict 37.45 and 36.07 kcal ∕ mol for Δ H f ( 0 K ) and Δ H f ( 298.15 K ) , respectively, in very good agreement with the inferred experimental values of 37.98 and 36.15 kcal ∕ mol . For HSBr, the estimate turns out to be 10.38 and 8.29 kcal ∕ mol for Δ H f ( 0 K ) and Δ H f ( 298.15 K ) , respectively. Using the more recent HBrO experimental heat of formation at 298.15 K of Lock , [ J. Phys. Chem. 100 , 7972 ( 1996 )] the inferred experimental value for HSBr is predicted to be 8.15 kcal ∕ mol , compared with 8.65 kcal ∕ mol derived from the data of Ruscic and Berkowitz [ J. Chem. Phys. 101 , 7795 ( 1994 )] . Considering the better agreement of the result with that predicted using the experimental value of Δ H f ( 298.15 K ) of Lock , the author also supports the suggestion made by Denis [ J. Phys. Chem. A. 110 , 5887 ( 2006 )] that the result of Lock should be preferred over the one of Ruscic and Berkowitz. For Δ H f ( 0 K ) , the author found 10.38 and 10.56 kcal ∕ mol , respectively, for the theoretical and inferred experimental estimates.