An experimental and theoretical study of the electronic and molecular structure of [Zn4(?4-S){mu-S2P(OC2H5)(2)}(6)]: the first molecular model of ZnS

The electronic and molecular structure of hexakis[mu-(O, O'-diethyl dithiophosphate-S:S')]-mu(4)-thiotetrazinc, [Zn-4(mu(4)-S){mu-S2P(OC2H5)(2)}(6)] (1), has been investigated by combining X-ray diffraction measurements, UV-vis absorption spectroscopy and density functional calculations. The title compound is characterized by a Zn-4(mu(4)-S)(mu-S-12) core consisting of a S atom at the center of a distorted tetrahedron of Zn ions, each of them placed at the center of an irregular tetrahedron of S atoms. Theoretical results point out that 1, at variance to the isostructural [Zn-4(mu(4)-S){mu-S2As(CH3)(2)}(6)] recently investigated by Albinati et al. [Inorg. Chem. 38 (1999) 1145], can be considered a well tailored molecular model of ZnS. Theoretical outcomes also indicate that the low energy region of the UV absorption spectrum of 1 includes transitions having a ligand-to-metal-charge transfer nature involving the excitation of an electron from the occupied mu(4)-S 3p based atomic orbitals to the empty Zn 4s based levels.