Electronic structure of ruthenium(II) polyynyl complexes.

Abstract

The electronic structure of the polyynyl complexes [Ru{(C equivalent toC)nR}(PH3)(2)CP] (n = 1-6; R = H, CH3, C6H5, C6H4NH2-P, C6H4NO2-P, CN), the diynyl compounds [Ru{(C equivalent toC)(2)R}CO)(2)CP], and the oxidized species [Ru{(C equivalent toC),C6H5}(PH3)(2)CP](+) have been studied using DFT methods. The optimized geometries are in good agreement with the few experimental structures available. The electronic structures are best described in terms of a strong sigma - bonding component and a weaker interaction between the filled metal d orbitals and filled polyyne pi orbitals. The charge distribution in the molecules and the energies and localization of the frontier orbitals have been examined to help rationalize the reactivity patterns emerging for this important class of compounds.