Platinum and rhodium complexes ligated by imidazolium-substituted phosphine as efficient and recyclable catalysts for hydrosilylation

Abstract

Phosphine ligands functionalized with imidazolium salt were prepared and used for the synthesis of two new ionic Pt(0) complexes and four Rh(i) complexes. The catalysts show very good catalytic activity in hydrosilylation reaction of olefins of different polarities (1-octene and allyl glycidyl ether) with 1,1,1,3,5,5,5-heptamethyltrisiloxane. Their insolubility in the reaction medium facilitated their isolation and permitted their multiple use in subsequent catalytic runs. In hydrosilylation of nonpolar olefins, all the catalysts showed similar activity, while in hydrosilylation of polar olefins the catalysts containing the bromide anion showed higher activity. The results permitted identification of the most effective catalysts for hydrosilylation of olefins of different polarities. The most active complexes did not lose their activity even after 10 catalytic runs, thereby providing a very good alternative to the commonly used homogeneous catalysts.