Selectivity of attack on a Si-C(sp3) sigma bond coordinated to NiII

(PNP)Ni+ (as its (BAr4F - salt) adds PhCN to Ni, but HX cleaves the Si-CH2 bond to form Ni[eta(2)((BuPCH2)-Bu-t-P-2-SiMe2)N(H)(SiMe2X)][eta(2)-(CH2Bu2P)-Bu-t](+), for X = OMe, piperidyl, N(H)CH2Ph, N(H)Ph, morpholinyl. The diprotic reagent H2O gives (eta(2)-(Bu2PCH2SiMe2OSiMe2NH2)-Bu-t)(eta(2)-(Bu2CH2P)-Bu-t)Ni+. RCCH (R = Ph, SiMe3, Bu-t) reacts, through three detected intermediates, to form ((Bu2PCH2SiMe2)-Bu-t)N(H)((SiMe2CH2Bu2PCCR)-Bu-t)Ni+, a product where one P has been oxidized and Ni reduced, each by two electrons. This shows the dominant influence on reactivity of Si-C bond activation by its unconventional donation to nickel in the structure of (PNP)Ni+. (C) 2011 Elsevier B.V. All rights reserved.