Tungsten carbonyl complexes of Main Group IV organometallic sulfides

Abstract

Vibrational spectroscopic data from the literature and from seven new compounds is treated by the methods of Cotton and Kraihanzel and of Graham. The results are interpreted as evidence that in (R3MSPh)W(CO)5 (R = Me, Ph: M = Si, Ge, Sn) there are W → S dπ–dπ and S → M pπ → dπ components to the bonding, the extent of the latter varying in the order Si > Ge > Sn. It is concluded that changes in the carbonyl stretching spectra reflect changes in electron density on sulfur. Thus, the carbonyl spectra are affected both by the electronegativity of groups bound to sulfur and by the extent of S → M π-bonding. The fact that changing M affects spectroscopic properties of a bond three atoms away represents long range transmission of effects via multiple bonds but in a manner quite unlike that in conjugated organic systems.