ELECTRONIC-STRUCTURE OF THIOMETALATES [MS4](N-) (M=MO, W, RE) - XANESSPECTRA AND SCF-X-ALPHA-SW CALCULATIONS

Sulfur K-edge XANES spectra of PPh4+ salts of the title species are re ported. Assignments for the characteristic positions in the spectra ar e given and discussed. The energies of the pre-edge peaks and the main absorption edges are used to determine the ''crystal-field' splitting energies DELTA, i.e. the energy difference between the 2e and 4t2 lev els (1.4 eV for [ReS4]-, 1.1 eV for [WS4]2-and [MoS4]2-) and the energ ies of some frontier orbitals (HOMO-LUMO region). These data are compa red with results from Xalpha calculations, electronic absorption and E SCA spectra.