Characterization of metal – metal and metal – ligand interactions in binuclear MnPt vinylidene complexes by molecular orbital and charge density analyses

Abstract

Density functional theory and the extended charge decomposition analysis (ECDA), the natural population analysis (NPA) as well as the quantum theory of atoms in molecules (QTAIM) were used to gain insight into the nature of metal–metal and metal–ligand interactions in binuclear manganese–platinum vinylidene complexes with phosphine ligands at the Pt atom: Cp(CO)2MnPt(μ-C=CHPh)(P-P) (1 P-P=(PPh3)2, 2 P-P=dppm). The complexes 1 and 2 can be represented as π-complexes of the Pt-phosphine moiety (M) with the metalla-allene ligand Cp(CO)2Mn=C=CHPh (L). The substitution of PPh3 groups at the Pt atom by dppm ligand leads to a growth of the L ← M back-interaction as the result of approaching the CO group at the Mn atom to the Pt atom induced by the decrease in steric disincentives caused by phosphine ligands. Topological analysis of the charge density points to the indirect metal – metal bonding mediated by a couple of the 2e-2c metal –carbon interactions and the semi-bridging coordinated carbonyl group.