The treatment of isocyanides with π-C5H5Ni(PPh3)R in benzene at room temperature gave the complexes, π-C5H5Ni(CNR′)[C(R)NR] (I), the products of isocyanide insertion into nickel-alkyl sigma bonds. The reactions of isocyanides with π-C5H5(PR3)I (R=Ph, Et, OPh) produced the salt-like complexes (II), formulated as [π-C5H5Ni(CNR′)(PR3)]I and [π-C5H5Ni(CNR′)2]I (R′ = Ph, Et). Based on the formation of (I) from the reactions of (II) with phenylmagnesium bromide, the mechanism of the insertion reaction of isocyanides into nickel-to-carbon bonds has been considered. © 1969.