Silica-Supported Bis(trialkylphosphine)platinum Oxalates. Photogenerated Catalysts for Hydrosilation of Olefins

摘要

A heterogeneous hydrosilation catalyst has been prepared by linking a photoactive Pt(C2O4)L2 complex to silica by using the functionalized ligand L = (OMe)3Si(CH2)2PE2. Unreacted surface hydroxyls were capped with inert SiMe3 groups in all experiments. The surface-attached oxalate complex has been completely characterized by C, P, and Si CP-MAS solid-state NMR spectroscopies. This shows that the complex binds to the surface with an intact coordination sphere. At maximum loading the NMR data suggest about 75% of the complexes binds to the surface with both L. Ultraviolet irradiation results in the loss of the oxalate ligand as CO2 and the formation of a surface-attached PtL2 species that can be trapped with CO to yield a supported PtL2(CO)2 species.