Catalysis of hydrosilylation Part XXXIV. High catalytic efficiency of the nickel equivalent of Karstedt catalyst [{Ni(eta-CH2=CHSiMe2)(2)O}(2) {mu-(eta-CH2=CHSiMe2)(2)O}]

The nickel equivalent of Karstedt catalyst [{Ni(eta-CH2=CHSiMe2)(2)O}(2){mu -(eta-CH2=CHSiMe2}(2)O}] (1) appeared to be a very efficient catalyst for d ehydrogenative coupling of vinyl derivatives (styrene, vinylsilanes, vinyls iloxanes) with trisubstituted silanes HSi(OEt)(3), HSiMe2Ph. The reaction o ccurs via three pathways of dehydrogenative coupling, involving formation o f an unsaturated compound as the main product as well as a hydrogenated ole fin (DS-1) pathway, hydrogenated dimeric olefin (DS-2) and dihydrogen (DC), respectively. The reaction is accompanied by side hydrosilylation. Stoichi ometric reactions of 1 with styrene and triethoxysilane, in particular synt hesis of the bis(triethoxysilyl) (divinyltetramethyldisiloxane) nickel comp lex 3 and the first documented insertion of olefin (styrene) into Ni-Si bon d of complex 3, as well as all catalytic data have allowed us to propose a scheme of catalysis of this complex reaction by 1. (C) 2000 Elsevier Scienc e S.A. All rights reserved.