An unprecedented aluminum hydroxide LAIMe(OH) (5; L = HC[(CMe)(2,6-iPr(2)C(6)H(3)N)](2)) has been prepared by the hydrolysis of LAlMeCl (4). For the preparation of 5, the reagents of KOH, water, and KH1 as well as the two-phase ammonia/toluene system, were used. Further reactions of 5 with CP2ZrMe2 (8) and Cp2ZrHCl in toluene lead to the intermolecular elimination of CH4 and H-2 and the formation of mu-O-bridged dinuclear aluminum and zirconium complexes [LAIMe(mu-O)ZrMeCp2] (6) and [LA1Me(mu-O)ZrClCP2] (7), respectively, in high yields. The crystal structure reveals that 5 is a monomer with terminal OH and Me groups. The X-ray structure analysis shows that 6 and 7 contain a bent Al-(mu-O)-Zr core with terminal Al-Me and Zr-Me or Zr-Cl arrangements. The methylalumoxane (MAO)-activated compounds 6 and 7 exhibit high catalytic activity for the polymerization of ethylene. Under comparable polymerization conditions, the MAO/6 and MAO/7 catalyst systems show considerably higher activity and much lower MAO:catalyst ratios than that of MAO/8.