Mononuclear Aluminum Hydroxide for the Design of Well-Defined Homogeneous Catalysts

• Published in: Journal of the American Chemical Society Vol. 127; no. 10; pp. 3449 - 3455
• Main Authors: Bai, Guangcai, Singh, Sanjay, Roesky, Herbert W, Noltemeyer, Mathias, Schmidt, Hans-Georg
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 16.03.2005; Amer Chemical Soc
• Subjects: Catalysis; Catalysts: preparations and properties; Chemistry; Chemistry, Multidisciplinary; Exact sciences and technology; General and physical chemistry; Physical Sciences; Science & Technology; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; OLEFIN POLYMERIZATION CATALYSTS; COMPLEXES; COCATALYSTS; ZIRCONOCENE; HYDROLYSIS; STRUCTURAL-CHARACTERIZATION; CRYSTAL-STRUCTURES; DERIVATIVES; CATION; TERT-BUTYLALUMINUM; Hydroxo complex; Molecular structure; Organic ligand; Aluminium Organic compounds; Complex catalyst; Experimental study; Chemical reactivity; Catalyst activity; X ray diffraction; Crystalline structure
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja043585w

An unprecedented aluminum hydroxide LAlMe(OH) (5; L = HC[(CMe)(2,6-iPr2C6H3N)]2) has been prepared by the hydrolysis of LAlMeCl (4). For the preparation of 5, the reagents of KOH, water, and KH, 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 H2 and the formation of μ-O-bridged dinuclear aluminum and zirconium complexes [LAlMe(μ-O)ZrMeCp2] (6) and [LAlMe(μ-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−(μ-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.