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Published February 16, 2011 | Supplemental Material
Journal Article Open

Cationic Alkylaluminum-Complexed Zirconocene Hydrides: NMR-Spectroscopic Identification, Crystallographic Structure Determination, and Interconversion with Other Zirconocene Cations


The ansa-zirconocene complex rac-Me_2Si(1-indenyl)_2ZrCl_2 ((SBI)ZrCl_2) reacts with diisobutylaluminum hydride and trityl tetrakis(perfluorophenyl)borate in hydrocarbon solutions to give the cation [(SBI)Zr(μ-H)_3(Al^iBu_2)_2]^+, the identity of which is derived from NMR data and supported by a crystallographic structure determination. Analogous reactions proceed with many other zirconocene dichloride complexes. [(SBI)Zr(μ-H)_3(Al^iBu2)_2]^+ reacts reversibly with ClAl^iBu_2 to give the dichloro-bridged cation [(SBI)Zr(μ-Cl)_2Al^iBu_2]^+. Reaction with AlMe_3 first leads to mixed-alkyl species [(SBI)Zr(μ-H)_3(AlMe_x^iBu_(2−x))_2^]+ by exchange of alkyl groups between aluminum centers. At higher AlMe_3/Zr ratios, [(SBI)Zr(μ-Me)_2AlMe_2]^+, a constituent of methylalumoxane-activated catalyst systems, is formed in an equilibrium, in which the hydride cation [(SBI)Zr(μ-H)_3(AlR_2)_2]^+ strongly predominates at comparable HAl^iBu_2 and AlMe_3 concentrations, thus implicating the presence of this hydride cation in olefin polymerization catalyst systems.

Additional Information

© 2011 American Chemical Society. Received: June 9, 2010. Published: January 18, 2011. This research was supported by the US DOE Office of Basic Energy Sciences (Grant DE-FG03-85ER13431), by the Deutsche Forschungsgemeinschaft (Grants Bri510/14-1 and Me1388/9-1), by Fonds der Chemischen Industrie, and by BASELL Polyolefine GmbH. The X-ray diffractometer was purchased via an NSF CRIF:MU award to the California Institute of Technology, CHE-0639094

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Supplemental Material - ja1050428_si_001.pdf

Supplemental Material - ja1050428_si_002.cif

Supplemental Material - ja1050428_si_003.cif


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