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Published June 4, 2007 | Supplemental Material
Journal Article Open

Dialkyl and Methyl-Alkyl Zirconocenes: Synthesis and Characterization of Zirconocene-Alkyls That Model the Polymeryl Chain in Alkene Polymerizations


Zirconocene precatalysts with sterically bulky alkyl groups were designed as model systems for the propagating species in zirconocene-catalyzed alkene polymerization. Specialty alkyllithium reagents Li(CH_2CEt_3) and Li(CH_2CMe_2CH_2Ph) were prepared and utilized in the synthesis of dialkyl and methyl-alkyl zirconocenes of the form CpCp^*ZrR_2, Cp_2Zr(CH_3)(R), and CpCp^*Zr(CH_3)(R) (Cp = (η^5-C_5H_5); Cp^* = (η^5-C_5Me_5); R = CH_2CMe_3, CH_2SiMe_3, CH_2CEt_3, CH_2CMe_2CH_2Ph). These new zirconocene alkyls were isolated and fully characterized by NMR spectroscopy and in some cases by X-ray diffraction. The molecular structures determined display the bent-sandwich coordination mode common for zirconocenes. The steric influence of the alkyl group on the observed structural parameters is reflected in slightly expanded C−Zr−C or C−Zr−Cl angles in the equatorial plane and long zirconium−alkyl bond distances.

Additional Information

© 2007 American Chemical Society. Received 10 February 2006. Published online 5 May 2007. Published in print 1 June 2007. This work has been supported by USDOE Office of Basic Energy Sciences (Grant No. DE-FG03-85ER13431), Exxon Chemicals America, and the National Science Foundation (Grant No. CHE-0131180). We wish to thank Professor Thomas Livinghouse for useful suggestions in the synthesis of the specialty alkyl lithiums, David Kurtz for preparation of organic precursors, and Paul Elowe for assistance with X-ray crystallographic figures.

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Supplemental Material - om0601302si20060210_073335.cif


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