Electronic structure of ruthenium(II) polyynyl complexes

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 diy nyl compounds [Ru{(C equivalent toC)(2)R}CO)(2)CP], and the oxidized specie s [Ru{(C equivalent toC),C6H5}(PH3)(2)CP](+) have been studied using DFT me thods. The optimized geometries are in good agreement with the few experime ntal 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 dis tribution in the molecules and the energies and localization of the frontie r orbitals have been examined to help rationalize the reactivity patterns e merging for this important class of compounds.