Base Metal-terpyridine Complex Immobilized on Stationary Phase Aimed as Reusable Hydrosilylation Catalyst

The catalytic activity of a base metal-terpyridine complex immobilized on silica gel (M(tpy)X2 @SiO2 /H2 O: M=Mn, Fe, Co, Ni, Cu; X=Cl, Br) for hydrosilylation was investigated. Co(tpy)Br2 @SiO2 /H2 O in the presence of NaBHEt3 exhibited the highest catalytic activity for hydrosilylation of 1-octene with diphenylsilane (Ph2 SiH2 ) to form the anti-Markovnikov-type hydrosilylation compound as the main product. The reusability of Co(tpy)Br2 @SiO2 /H2 O activated by NaBHEt3 was examined. It was found that the catalytic activity decreased with repeated use because of the peeling off of the Co complex anchor portion from the silica gel surface upon the attack of NaBHEt3 . The introduction of Co(OAc)2 instead of CoBr2 to silica gel formed Co(tpy)(OAc)2 - and Co(tpy)(OH)2 -immobilized silica gel, which exhibited catalytic activity for the hydrosilylation in the absence of an activator such as NaBHEt3 . The glassware in which Co(tpy)(OH)2 was immobilized on the inner wall was prepared. It was found that the hydrosilylation catalytically occurred on the surface of a pretreated glassware and that the catalytic activity did not decrease even after 10 repeated uses.