Coordination Ability of Phosphavinyl(oxo and thioxo)phosphoranes (P═C–P═X; X = O, S) toward Transition Metals

The coordination preferences of phosphavinylphosphorane species with the Mes*P═C(Cl)–PR1,R2(═X) general formula (Mes* = 2,4,6-trit-butylphenyl; X = O, S; R1 = Cl, R2 = 2,4,6-trii-propylphenyl; R1 = R2 = i-propyl) were evaluated in the presence of Au, W and Pd transition metals, by means of both experimental and theoretical investigations. Targeted compounds were characterized in solution by multinuclear NMR spectroscopy and HRMS, while for several cases, the solid-state structures were measured through X-ray diffraction. The preference for the coordination through the sulfur lone pair toward gold fragment was observed in the solid state, yet computational data highlight a possible fluxional character occurring in solution. Density functional theory mechanistic explorations suggest that the AuCl moiety shuttles between the P(III) and S atoms. Tungsten phosphavinylphosphorane complexes are stabilized by the phosphavinylphosphorane ligands in a bidentate coordination mode, involving both the P(III) and chalcogen atom. The coordination compounds with palladium fragments lead to the corresponding chelate compounds and the subsequent activation of a C–H bond from an ortho-methyl group of the Mes* group was observed if the P═C–P(═X) unit contained a Cl or O atom on the P(V) atom.