Platinum(II)-bis-(N-heterocyclic carbene) complexes: synthesis, structure and catalytic activity in the hydrosilylation of alkenes

Chelating biscarbene ligands increase the stability of metal-organic catalyst systems. The catalytic activities of seven structurally different platinum(II)-bis-NHC-complexes in the hydrosilylation of alkenes have been investigated and compared with the catalytic activity of the Karstedt catalyst and of a highly active platinum(0)-NHC-complex. It is shown that a fine-tuning of the catalytic activity of the platinum(II)-bis-NHC-complexes is possible. The synthesis of a platinum(II)-bis-NHC-complex with similar activity, but additional advantages compared to the Karstedt catalyst, is reported. The solid state structure of 1,1-[Bis(3,3′-(4-methoxyphenyl)-1,1′-1H-imidazolium-2,2′-ylidene)methanediyl]platinum(II)-dichloride is presented.