An SCF-Xα scattered wave study of the electronic structure and iron quadrupole splitting in the [Fe(MoS4)Cl2]2− ion

Abstract

Spin restricted and spin polarised SCF MS-Xα calculations have been performed to investigate the electronic structure and iron nuclear quadrupole coupling tensor of the [Fe(MoS4)Cl2]2− dianion. It is found that both the spin restricted and spin polarised models predict a ground state quintet (S = 2) in agreement with that observed experimentally with similar overall charge distributions. However the calculated quadrupole coupling tensor varies in magnitude and sign between the two calculations. The spin polarised calculation gives values of the quadrupole coupling tensor that agree well both in magnitude, sign, and direction with those reported from single crystal Mössbauer spectroscopy. The principal direction of the electric field gradient tensor is found to be sensitive to the relative occupations of the iron dz2 and dx2-y2 orbitals (which are mixed under C2V symmetry).