REACTION CONTROL OF ORGANOMETALLIC COMPLEXES RELEVANT TO CATALYTIC HYDROSILYLATION

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(1) All elementary processes responsible for ruthenium complex-catalyzed hydrosilylation of terminal alkynes have been identified by means of NMR analysis of catalytic solutions as well as model studies ofpresumed catalytic intermediates. The catalytic reactions yield (E)- and (Z)-alkenylsilanes, and relative ratio of these two stereoisomers of hydrosilylation products clearly depends on the reaction-courses of alkenylruthenium intermediates with hydrosilanes. Thus, there are two reaction-courses C-H bond formation with concomitant generation of a silylrutheinum intermediate via a sequence of oxidative addition and reductive elimination. Based on the mechanistic findings, highly efficient catalysts giving (E)- and (Z)-alkenylsilanes, independently, in 91-99% stereoselectivties have been developed. Catalytic performance of the newly developed catalysts has been demonstrated for stereocontrolled synthesis of (E)- and (Z)-rich poly (p-phenylenevinylene)s, which are highly expected electroptical materials(2) Novel palladium and platinum hydrides of rather unique catalytic properties have been prepared by the treatment of the methyl triflate complexes exhibit high catalytic activity for hydroamination of conjugated dienes, dehydrogenative silylation of ketones, and direct conversion of allylic alcohols(3) A variety of silylplatinum complexes have been prepared, and their reactivities toward C-Si reductive elimination and alkyne-insertion have been examined in detail by kinetic experiments. The silylplatinum complexes have been found to be highly reactive, as compared with the corresponding organoplatinum complexes having a platinum-carbon bond