A Convenient Method for the Synthesis of Zirconocene Hydrido Chloride, Isobutyl Hydride, and Dihydride Complexes Using tert-Butyl Lithium

Jaime A. Pool, Christopher A. Bradley, and Paul J. Chirik*
Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853
Organometallics, 2002, 21 (6), pp 1271–1277
DOI: 10.1021/om011090z
Publication Date (Web): February 21, 2002
Copyright © 2002 American Chemical Society
*

In papers with more than one author, the asterisk indicates the name of the author to whom inquiries about the paper should be addressed.

Abstract

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Preparation of zirconocene hydrido chloride complexes has been accomplished via addition of 1 equiv of tert-butyllithium to the corresponding zirconocene dichlorides. In this manner, both Cp*Cp‘ ‘Zr(H)Cl and Cp‘ ‘2Zr(H)Cl (Cp* = C5Me5, Cp‘ ‘ = 1,3-(SiMe3)2C5H3) were prepared in high yield. Further addition of tBuLi to Cp*Cp‘ ‘Zr(H)Cl affords the isobutyl hydride complex Cp*Cp‘ ‘Zr(CH2CHMe2)(H), which upon addition of 1 atm of dihydrogen undergoes rapid hydrogenolysis yielding the monomeric dihydride Cp*Cp‘ ‘ZrH2. In the absence of dihydrogen, the zirconocene dihydride undergoes reversible C−H activation of a cyclopentadienyl trimethylsilyl group, affording the “tuck-in” derivative Cp*(η5-1-SiMe3C5H3-3-(η1-SiMe2CH2))ZrH. Addition of 2 equiv of tBuLi to the ansa-zirconocene iPr2Si(η5-3-SiMe3C5H3)(η5-3,4-(SiMe3)2C5H2)ZrCl2 results in the corresponding zirconocene isobutyl hydride complex, which upon exposure to H2 affords the dimeric dihydride [iPr2Si(η5-3-SiMe3C5H3)(η5-3,4-(SiMe3)2C5H2)ZrH2]2. In a similar procedure the substituted indenyl complexes rac-(1-CMe3−C9H6)Zr(H)Cl and rac-(1-CMe3−C9H6)Zr(CH2CHMe2)(H) have been prepared. This synthetic methodology allows for the preparation of metallocene alkyl hydrides and dihydrides inaccessible by more traditional routes.

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History

  • Published In Issue March 18, 2002
  • Received December 27, 2001

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