Highly Efficient and Reusable Alkyne Hydrosilylation Catalysts Based on Rhodium Complexes Ligated by Imidazolium-Substituted Phosphine

Abstract

Rhodium Rhodium complexes complexes ligated ligated by imidazolium-substituted by imidazolium-substituted phosphine phosphine were used were as catalysts used as in catalysts the hydrosilylation in the hydrosilylation of alkynes of (1-heptyne, alkynes (1-heptyne, 1-octyne, and 1-octyne, phenylacetylene) and phenylacetylene) with 1,1,1,3,5,5, with 5-heptamethyltrisiloxane 1,1,1,3,5,5,5-heptamethyltrisiloxane (HMTS) or (HMTS) triethylsilane or triethylsilane (TES). In all cases, (TES). the In above all complexes cases, the showed above higher complexes activity showed and selectivity higher activity compared and selectivity to their precursors compared ([Rh(PPh to their precursors 3)3Cl] and [{Rh(µ-Cl)(cod)} ([Rh(PPh3)3Cl] and 2]). In [{Rh(µ-Cl)(cod)}2]). the reactions with In aliphatic the reactions alkynes with (both aliphatic when alkynes HMTS (both and TES when were HMTS used and as hydrosilylating TES were used agents), as hydrosilylating β(Z) isomer agents), was mainly β(Z) isomer formed, was but, mainly in the formed, reaction but, of phenylacetylene in the reaction of with phenylacetylene TES, the β(E) product with TES, was the formed. β(E) product The catalysts was formed. are very The durable, catalysts stable are in very air durable, and first stable and foremost in air and insoluble first and in the foremost reactants insoluble which facilitated in the reactants their isolation which facilitated and permitted their their isolation multiple and use permitted in subsequent their multiple catalytic runs. use in They subsequent make a very catalytic good runs. alternative They to make the commonly a very good used alternative homogeneous to the catalysts. commonly used.