Potential for rotation about C( sp2)S bonds: electron-diffraction results for OC(SCH 3) 2 and ab initio calculations on OCHSH and SCHSH

Abstract

Gaseous S,S′-dimethyldithiocarbonate, OC(SCH 3) 2, has been investigated using electron diffraction and the experimental data are consistent with a syn-syn conformation. The most important structural parameters are: r a(CO) = 1.206(4) Å, r a(C carbS) = 1.777(3) Å, r a(C MeS) = 1.802(4) Å, ∠ OCS = 124.9(2)° and ∠ CSC = 99.3(4)°. The standard deviations are given in parentheses. Ab initio calculations have been carried out on monothioformic acid, OCHSH, and dithioformic acid, SCHSH. The calculations gave energy minima for syn and anti forms.