A convenient route to vinylsiloxane-tertiary phosphine-nickel(0) complexes; the molecular structure of [(Ni{P(C6H4Me-4)3})2{μ-(L′′L′′)2}] {(L′′L′′)2=[CH2CH(Me)Si(μ-O)]4}

A simple one pot synthesis in Et2O at ambient temperature, from the readily available starting materials [Ni(cod)2], PR3 and LL or (L′′L′′)2, provides an essentially quantitative route to the known vinylsiloxanenickel(0) complexes [)PR3] and the new binuclear analogues [{Ni(PR3)}2{μ-(L′′L′′)2}] (5) {LL=[CH2i]2O, (L′′L′′)2=[CH2i(μ-O)]4 and R=Ph, C6H4Me-4 or C6H11-c}. The X-ray crystal structure of 5b (R=C6H4Me-4) shows it to be a centrosymmetric binuclear complex containing (L′′L′′)2 as a chair-shaped bridging ligand. It is bound to each Ni(PR3) moiety by a pair of μ2-vinyl groups (having M and M′ as centroids) and each NiMSiOSi′M′ metallacycle is also of chair conformation.