Theoretical predictions of the molecular structure of sulphur tetrafluoride

Abstract

The equilibrium geometry of the SF₄ molecule has been investigated by means of ab initio electronic structure theory. Self-consistent-field (SCF) calculations employing a minimum basis set (MBS) incorrectly predict SF₄ to have a square- pyramidal (C_4V) structure. The correct qualitative prediction of a C_2V geometry is obtained with a basis of nearly double zeta quality. Comparable calculations on H₂S and SF₂ suggest that it may only be for hypervalent molecules containing sulphur that minimum basis sets are inappropriate. However, polarization functions seem to be necessary for an accurate prediction of S-F bond distances.