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

Abstract

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

A family of rhodium(i) NHC chelates featuring O-containing tethers for catalytic tandem alkene isomerization–hydrosilylation

“…Nevertheless, the subtle changes in the nature of the O-containing pendant arm are found to be responsible for the substantial differences in the catalytic activity of these compounds. Rh(I) NHC species have been used as catalysts in hydrosilylation processes of carbonyls 22,52,53 , alkynes [54][55][56][57] and alkenes. [21][22][23] Encouraged by these precedents, we decided to evaluate which structural factors are critical for the alkene hydrosilylation performances of the present family of catalysts.…”

Transition-Metal-Catalyzed Stereo- and Regioselective Hydrosilylation of Unsymmetrical Alkynes

“…The Rh catalysts gave mainly -Z-selectivity in hydrosilylation of terminal alkynes (Table 3, entries 1-10), 43,[45][46][47][48][49][75][76][77][78][79] which was greatly different from Pt catalysts (Table 1, entries 1-14). The Rh(I) and Rh(III) complexes were suitable catalysts for this purpose.…”

Ionic Liquids in Catalysis

“…In the next two papers, heterogeneous catalysts containing ionic liquids as structural elements were described. Bartlewicz et al [34] presented a rhodium complex ligated by imidazolium-substituted phosphine that showed high activity for hydrosilylation of alkynes. A series of anionic platinum complexes obtained by a simple reaction of piperidinium or pyrrolidinium ionic liquids with platinum compounds were presented by Jankowska-Wajda et al [35].…”