Synthesis, Structure, and Reactivity of (^tBu₂PC₂H₄P^tBu₂)Ni(CH₃)₂ and {(^tBu₂PC₂H₄P^tBu₂)Ni}₂(μ-H)₂

Oxidative addition of CH3I to (dtbpe)Ni(C2H4) (dtbpe = tBu2PC2H4PtBu2) affords (dtbpe)Ni(I)CH3 (1). The reaction of (dtbpe)NiCl2 or 1 with the stoichiometric quantity of (tmeda)Mg(CH3)2 yields (dtbpe)Ni(CH3)2 (2). (dtbpe)Ni(I)CD3 (1-d3) and (dtbpe)Ni(CD3)2 (2-d6) have been prepared analogously. Thermolysis of 2 in benzene affords {(dtbpe)Ni}2(μ-η2:η2-C6H6) (4). The reaction of either 2 or 4 with hydrogen (H2, HD, D2) gives {(dtbpe)Ni}2(μ-H)2 (3) and the isotopomers {(dtbpe)Ni}2(μ-H)(μ-D) (3-d) and {(dtbpe)Ni}2(μ-D)2 (3-d2). According to the NMR spectra, the structure of 3 is dynamic in solution. The crystal structures of 2 and 3 have been determined by X-ray crystallography. Solution thermolysis of 2 or reduction of (dtbpe)NiCl2 with Mg* in the presence of alkanes probably involves σ-complex-type intermediates [(dtbpe)Ni(η2-R‘H)] (R‘ = e.g. C2H5, A). While the nonisolated [(dtbpe)Ni0] σ-complexes A are exceedingly reactive intermediates, isolated 3 and 4 represent easy to handle starting complexes for [(d...