CONTROL OF THE CATALYTIC HYDROSILYLATION OF PHENYLACETYLENE WITH P-LIGANDS USING NICKEL(0) CATALYST

We report here the first systematic investigation of the effects of concentration and properties of tertiary phosphines on the chemoselectivity of the homogeneous catalytic hydrosilylation of phenylacetylene with triphenylsilane using Nickel(0) catalyst. The presence of P-ligands is necessary to activate the catalytic system. Between the ligand/metal ratio 1/1-2/1 hydrosilylation of phenylacetylene is preferred to trimerisation. The three-dimensional ligand profile showed that phosphines with decreasing bulkiness control the products of hydrosilylation but phosphines with increasing bulkiness yield trimers of acetylene. Hydrosilylation is enhanced when the P-ligand is either more basic or less basic than triphenylphosphine. It was found that tertiary n-alkyl-and n-alkoxy-phosphines using a ligand/metal ratio 2/1 in the presence of HSiPh3/PhC=CH = 2/1 product 85-90% hydrosilylation selectivity in preference to phenylacetylene.