The gas-phase acidities of substituted dithiosilanoic acids (X–SiSSH, X=H, F, Cl, OH, NH2 and CH3)

Ab initio molecular orbital calculations at the CBS-Q level of theory have been used to study the rotational conformers and acidity of dithiosilanoic acid and several of its derivatives R–SiSSH (R=H, F, Cl, NH2, OH and CH3). For all six acids studied the syn conformers are predicted to have the lowest energy. The syn–anti enthalpy difference varies between 4 and 7 kJ mol−1. Dithiosilanoic acid is ∼60 and ∼96 kJ mol−1 more acid than dithioformic and silanoic acid, respectively.