Carbene complexes. Part I. Electron-rich olefins as a source of carbene complexes of platinum(II) and palladium(II); and some experiments with (CF3)2CN2

The reactions of electron-rich olefins with di-µ-chloro-dichlorobis(phosphine)diplatinum(II)(and bromo-, arsine-, and PdII analogues) have been investigated. In general, the product is the trans-PtII or PdII carbene complex, or the cis-isomer, or a mixture of these compounds, depending on the reagents, solvent, and reaction conditions. The compounds are stable, crystalline, and monomeric. Bis(trifluoromethyl)diazomethane reacts with (i) di-µ-chloro-dichlorobis(triethylphosphine)diplatinum(II) to give the product of insertion only into the terminal Pt–Cl bonds, and (II) tris(triphenylphosphine)platinum(0) to furnish the adduct Pt(CF3)2CN2·(CF3)2C(PPh3)2. Structures and mechanisms are discussed.