An Adaptable Chelating Diphosphine Ligand for the Stabilization of Palladium and Platinum Carbenes

Group 10 metal carbenes are proposed in catalytic transformations; however, their isolation remains difficult without the presence of a heteroatom donor. The adaptable cis and trans coordinating ligand (PP)-P-ter (1,2-bis(2-(diisopropylphosphino)phenyl)benzene) is key in stabilizing two-coordinate palladium and platinum(0) precursors. Reacting these precursors with di-p-tolyldiazomethane ((p-tol)(2)CN2) leads to the formation of the unprecedented trigonal-planar diarylcarbenes [((PP)-P-ter)M=C(p-tol)(2)] (M = Pd, Pt), upon transformation of the trans coordinating ligand into a wide-bite, cis-coordinating ligand. Both palladium and platinum diarylcarbenes were characterized by multinuclear NMR spectroscopy. The unusual stability of the platinum analogue allowed its characterization via X-ray crystallography. Furthermore, the reactivity of the palladium and platinum diarylcarbenes with Ph2SiH2 and CH3I was investigated.