Complexation of Cp2MCl2 in a Chloroaluminate Molten Salt: Relevance to Homogeneous Ziegler-Natta Catalysis
FRANK J SEILER RESEARCH LAB UNITED STATES AIR FORCE ACADEMY CO
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Ethylene polymerization via Ziegler-Natta catalysis occurs in the ambient-temperature molten slat AlCl3-MEIC employing Cp2TiCl2 as the catalyst occurs only in melts with AlCl3MEIC molar ratios. Cp2ZrCl2 and Cp2HfCl2 with AlCl3-XrX cocatalysts are not catalytically active in acidic melts. 1H NMR studies indicate formation of a strong 11 complex between Cp2TiCl2 and AlCl3, while Zr and Hf form much weaker 11 complexes due to strong Zr - Cl and Hf - Cl bonding. This stronger M - Cl bonding for Zr and Hf is proposed to preclude the initiation reaction for ethylene polymerization n the molten salt.
- Polymer Chemistry