Reactions of organic halides and cyanides with bis(tricyclohexylphosphine)nickel(0).

The reactions of the complex bis(tricyclohexylphosphine)nickel(0) (Ni(PCy3)2) with organic halides and cyanides RX (R  CH3, X  I, CN; R  C2H5, X  Br, I, CN; R  C3H7, X  Br, CN; R  C6H5, X  Cl, CN), all involving fission of the RX bond, have been studied in toluene at various temperatures. Oxidative addition of the bromides produces the stable complexes [NiIBr(PCy3)2]2 and NiII (H)(Br)(PCy3)2. Methyl iodide affords phosphonium salts of a nickel(II) complex. The organic products of these reactions involve alkanes, alkenes, benzene, and reductive coupling products RR. Except for the methyl and phenyl derivatives the distribution of organic products is rather insensitive to the functional group X. The reactions are discussed in terms of molecular and radical mechanisms. The reactivity of Ni(PCy3)2 is compared with that of Ni(PEt3)3 and Ni(PMe3)4.