Feng Rulin, Vasiliu Monica, Peterson Kirk A, Dixon David A
Department of Chemistry, Washington State University , Pullman, Washington 99164-4630, United States.
Department of Chemistry, The University of Alabama , Shelby Hall, Tuscaloosa, Alabama 35487-0336, United States.
J Phys Chem A. 2017 Feb 9;121(5):1041-1050. doi: 10.1021/acs.jpca.6b11889. Epub 2017 Jan 27.
Gas-phase acidities and aqueous solution pK's are predicted for MO(OH), where the center atom M is a main Group 6, 16, and U atom using the Feller-Peterson-Dixon approach based on coupled cluster CCSD(T) calculations with additional corrections. The gas-phase acidities of the MO(OH) compounds are essentially the same for elements (M) of the same group, 304-310 kcal/mol at 298 K. All of the Group 6 compounds are 5-6 kcal/mol less acidic in the gas phase than HSO. The gas-phase acidity of UO(OH) is calculated to be up to 338.0 kcal/mol, ∼10% less acidic in the gas phase than the other MO(OH) acids. The most acidic molecule in aqueous solution is predicted to be HSO. Overall, for the Group 16 compounds, the pK's increase going down the group, with HPoO predicted to be slightly more acidic than nitric acid. HCrO is the most acidic of the Group 6 transition metal compounds. The aqueous acidities of HMoO and HWO are comparable and about 3 pK units less acidic than HCrO and comparable in acidity to HNO. HUO is not acidic at all in aqueous solution with a pK near 20 pK units and is also not predicted to readily undergo hydrolysis reactions.
