Vibrational and Electronic Spectroscopy of Neutral Antimony Coordination Compounds of the 1,3-Dithiole-2-thione-4,5-dithiolate (dmit)

The S 1s X-ray absorption near edge structure (XANES) and X-ray photoelectron spectra (XPS) of the neutral complexes [SbL­(dmit)] (L = Br or I; dmit =1,3-dithiole-2-thione-4,5-dithiolate) have been measured using tunable synchrotron radiation. The valence shell electronic excitation by ultraviolet–visible (UV–vis) spectroscopy and the infrared vibrational spectra are presented and analyzed. The UV–vis results lead to an assignment of bands at 400 nm as πSm → π*CS, where Sm is the thiolate sulfur. The corresponding S 1s → π*CS transition was identified at 2468.3 eV. Ab initio calculations, within the improved virtual orbital (IVO) method, carried out with the GSCF3 program, were applied to establish a complete and accurate spectral assignment. It has been the first attempt to apply such methodology for dmit coordination compounds, and very consistent results were obtained.