Reactions of methyl and ethyl halides with the complexes Ni[P(C2H5)3]4 and Ni(X)[P(C2H5)3]3.

The rates of the thermal reaction of the nickel(0) complex Ni[P(C2H5)3]4 with the alkyl halides CH3Br, CH3I in toluene have been compared with those of the reactions of the nickel(I) complexes Ni(X)[P(C2H5)3]3 (X  Br,I). The organic products from CH3X are methane and ethane, and those from C2H5I are ethane and ethylene. The reactivity of the nickel(I) complexes is 10–20 times less than that of the nickel(0) complex. The result suggest that the first step of the reaction of nickel(0) with CH3I is the expected oxidative addition of the halide to the metal substrate. The intermediate thus formed decomposes to produce ethane (and small amounts of methane) without further reaction with the organic halide. This mechanism is supported by deuterium-labeling experiments.