Synthesis of the Binuclear Half-Metallocene Chromium(III) Aryloxides [Cp′Cr(OAr)Cl]<sub>2</sub> and Their Catalytic Properties for Ethylene Polymerization in the Presence of Alkylaluminum Cocatalyst
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A number of new chloride-bridged binuclear half-metallocene chromium(III) aryloxide complexes [Cp′Cr(OAr)Cl]2 (Cp′ = C5H5 (1, 2), C5Me5 (3, 4); Ar = 2,6-iPr2C6H3 (1, 3), 2,6-tBu2C6H3 (2, 4)) have been synthesized from the reaction of Cp′CrCl2(THF) with the lithium salt of the corresponding aryloxide ligand in THF. All complexes have been characterized by elemental analyses, 1H NMR, IR, and UV−vis spectroscopy. The molecular structures of complexes 1 and 3 were determined by X-ray crystallography. Upon activation with a small amount of AlR3, all complexes 1−4 show high catalytic activity for ethylene polymerization, producing high-molecular-weight polyethylene. The effects of polymerization conditions such as polymerization temperature, alkyl aluminum cocatalyst, and Al/Cr molar ratio on the catalytic activity and properties of the produced polyethylene were investigated.
