Alkyl transfer reactivity in the first octahedral isocyanide complex of nickel(II)

[Ni{S2P(OEt)(2)}(2)] (1) reacts with 2 equiv of CNXyl (Xyl = 2,6-dimethylphenyl) to afford [Ni{S2P(OEt)(2)}(2)(CNXyl)(2)] (2), which, as confirmed by X-ray crystallography, is the first octahedral isocyanide complex of Ni(H). Reaction of 2 with PCy3 (2 equiv) produces square-planar [Ni{S2P(O)(OEt)} (PCy3)(CNXyl)] (3). When 2 is reacted with only I equiv Of PCy3, the final product is the square-planar complex [Ni{S2P(O)(OEt)}(CNXyl)(2)] (4), containing two isocyanide ligands. Compound 4 reacts with 2-fold excess PCy3 to give 3 via isocyanide displacement. Both 3 and 4 contain one ethyldithiophosphate ligand, which is produced by the transfer of one ethyl group from a coordinated diethyl dithiophosphate of complex 2 to the leaving diethyl dithiophosphate ligand. Experimental evidence indicates that the phosphine plays a significant role in the alkyl transfer. Moreover, reaction of I with 2 equiv of N-p-tolyl-2-iminopyridine affords octahedral [Ni{S2P(OEt)(2)}{2-pyCH=NC6H4-Me-4}(2)][S2P(OEt)(2)] (5), in which both free and coordinated diethyl dithiophosphate coexist without any transfer of alkyl.