Aluminum-nickel bonded intermediates in the Ziegler Nickel Effect: Mechanistic support from catalyzed hydroalumination and carbalumination reactions

The interaction of nickel(0) complexes with aluminum alkyls or hydrides to generate aluminum-nickel bonded intermediates is supported by three lines of evidence: (1) the Ni-H bond observed in the H-1 spectrum of mixtures of (Et(3)P)(4)Ni and (i)Bu(2)AlH; (2) the efficient carbalumination of benzonitrile effected by mixtures of (i)Bu(3)Al and (Cod)(2)Ni vs. no carbalumination by (i)Bu(3)Al alone; (3) the efficient synergistic hydrogen transfer between 9,10-dihydroanthracene and diphenylacetylene promoted only by mixtures of (i)Bu(3)Al and (Cod)(2)Ni. These observations provide strong evidence that intermediates of the type R(2)Al-NW and R(2)Al-Ni-H could very well be the causative agents in the Ziegler Nickel Effect.