Kinetic studies on the hydrosilylation of phenylacetylene with R3SiH (R-3 = PhMe2, Ph2Me, Ph-3, Et-3) using bis(1,2-diphenylphosphinoethane)norbornadiene rhodium(I) hexafluorophosphate as catalyst

Product distribution and kinetic studies on the hydrosilylation of phenylac etylene by Ph3SiH, Ph2MeSiH, PhMe2SiH and Et3SiH mere performed using bis-[ 1,2-diphenylphosphinoethane]norbornadienerhodium(I) hexafluorophosphate, 1, as catalyst. Pre-equilibration of the catalyst with the acetylene produced hydrosilylations, pre-equilibration with the silane did not. The catalyst showed a pronounced selectivity for cts-addition to form beta-products. t-P hCH=CHSiR3, unlike most hydrosilylation catalysts, The kinetic studies show ed a hydrosilylation reaction that is zero order with respect to both acety lene and the silane, with a dependency upon catalyst concentration. The k(o bs) value is directly influenced by the substituents on the silane: k(PhMe2 SiH) > k (Et3SiH > k (Ph2MeSiH) > k (Ph3SiH). Intercalation of the catalyst in hectorite was not useful, since either no reaction occurred in non-pola r solvents, or extraction of the catalyst occurred in polar solvents to pro duce the same product distributions. Copyright (C) 2000 John Wiley & Sons, Ltd.