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 \ue5fb CH3, X \ue5fb I, CN; R \ue5fb C2H5, X \ue5fb Br, I, CN; R \ue5fb C3H7, X \ue5fb Br, CN; R \ue5fb C6H5, X \ue5fb Cl, CN), all involving fission of the R\ue5f8X 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