ALUMINUM-NICKEL BONDED INTERMEDIATES IN THE ZIEGLER NICKEL EFFECT - MECHANISTIC SUPPORT FROM CATALYZED HYDROALUMINATION AND CARBALUMINATIONREACTIONS

The interaction of nickel(0) complexes with aluminum alkyls or hydride s to generate aluminum-nickel bonded intermediates is supported by thr ee lines of evidence: (1) the Ni-H bond observed in the H-1 spectrum o f mixtures of (Et(3)P)(4)Ni and (i)Bu(2)AlH; (2) the efficient carbalu mination 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 syn ergistic hydrogen transfer between 9,10-dihydroanthracene and diphenyl acetylene promoted only by mixtures of (i)Bu(3)Al and (Cod)(2)Ni. Thes e 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 t he Ziegler Nickel Effect.