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[?-(O,O?-diethyl dithiophosphate-S:S?)]-?4-thiotetrazinc, [Zn4(?4-S){?-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 Zn4(?4-S)(?-S12) 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 [Zn4(?4-S){?-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 ?4-S 3p based atomic orbitals to the empty Zn 4s based levels.