<i>d</i> Orbitals in Compounds of Second-Row Elements. I. SF6

Abstract

Optimum exponent values for 3s, 3p, and 3d orbitals of sulfur in SF6 have been calculated in an electrostatic approximation. The sulfur electrons are perturbed by fluorine potentials appropriate to self-consistent field wave functions for the fluorine orbitals, and the energy minimized with respect to wave-function exponents. The optimum values are k3s=2.0, k3p=1.6, and k3d=1.2, corresponding to expansion of 3s and 3p orbitals, and contraction of 3d, compared with free-atom values. The values are remarkably stable to changes in valence-orbital configurations as between SF6, S+F6−, S++F6=, and even S−F6+. They are also little affected by change in hybridization at fluorine, and should therefore be suitable for use in the construction of molecular wave functions. Although the calculated energies include no exchange terms they are still of some interest. They suggest for example that the promotion energy to the configuration sp3d2 of sulfur (estimated to be 25–31 eV) can be compensated by the energy of molecule formation.