A Paramagnetic Nickel–Zinc Hydride Complex

Reaction of a molecular zinc–hydride [{(ArNCMe)2CH}ZnH] (Ar = 2,6-di-isopropylphenyl) with 0.5 equiv. of [Ni(CO)Cp]2 led to the isolation of a nickel–zinc hydride complex containing a bridging 3-centre,2-electron Ni–H–Zn interaction. This species has been characterized in the solid-state by single crystal X-ray diffraction. DFT calculations are consistent with its formulation as a -complex derived from coordination of the zinc–hydride to a paramagnetic nickel(I) fragment. Continuous wave and pulse EPR experiments suggest that this species is not stable in solution and hint that the coordination event may well be dynamic. Further experiments show that in the presence of catalytic quantities of nickel(I) precursors, zinc–hydride bonds can undergo either H/D-exchange with D2 or dehydrocoupling to form Zn–Zn bonds. In combination, the data support the activation and functionalisation of zinc–hydride bonds at nickel(I) centres.