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

Abstract

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 mu-O-bridged dinuclear aluminum and zirconium complexes [LAlMe(mu-O)ZrMeCp2] (6) and [LAlMe(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.

Oxide‐Bridged Heterobimetallic Aluminum/Zirconium Catalysts for Ethylene Polymerization

“…The first structurally authenticated Al-O-Zr complex was obtained by Roesky and co-workers through reaction of a terminal aluminum hydroxide with dimethylzirconocene through methane elimination [Equation (3)]. [34,35] The aluminum hydroxide precursor in this reaction is sterically stabilized by the well-known, very protective β-diketiminate ligand DIPP-nacnac (CH{(CMe)-(2,6-iPr 2 C 6 H 3 N)} 2 ). The obtained Al-O-Zr species can be used as an ethylene polymerization catalyst but still needs to be activated by MAO.…”

Synthesis and Structural Characterization of Compounds Containing the Al–O–Al Motif

“…Commercially available chemicals were purchased from Aldrich, Fluka and used as received. LH, [16] LAlMe 2 , [8] and LAlH 2 [17] were prepared as described in literature. 1 H NMR spectra were recorded with a Bruker AM 400 spectrometer.…”

“…[6] Subsequently, more and more μ-oxo-bridged heterobimetallic complexes exhibiting the Al-O-M motif (M = Mg, Ti, Zr, Hf) were reported. [7,8] Furthermore, the μ-oxo-bridged homobimetallic complexes containing the Al-O-Al skeleton were also studied in recent years. [9,10,11] Herein, based on our previous research results, [12] we report on the synthesis of dialuminoxanes by the reaction of LAlMe 2 (1) or LAlH 2 (2) [L = HC(CMeNAr) 2 , Ar = 2,6-iPr 2 C 6 H 3 ] with water coming from the dehydration of organic boronic acid and stannanediol.…”

Preparation of the hydrocarbon-soluble trifluoro complex LTiF3 with a β-diketiminato ligand

“…The data were reduced (SAINT) [21] and corrected for absorption (SADABS) [22]. The structure was solved by direct methods, and refined against F 2 with anisotropic non-hydrogen atoms.…”