The Origin of the Unusual C4ν Structure Predicted for SH4

Abstract

Ab initio molecular orbital calculations have been performed on C2v and C4v isomers of SH4, SF4 and S(CH3)4 to investigate the origin of the different structures adopted by these molecules. We propose an electrostatic model similar in spirit to the VSEPR approach; this implies that the net charges on the ligands L in SL4 compounds can control the geometry of these compounds. Steric factors may also be significant. Even though the net charges on hydrogen and on the CH3 group are similar when these act as ligands towards sulfur, the carbon atom in the methyl group bears a substantial negative net charge, which has important structural consequences. Binding energies and structural parameters are presented for SH4 which are obtained from more complete theoretical calculations than those previously reported.