Carbon-oxygen bond cleavage with η95- bis(indenyl)zirconium sandwich complexes

Christopher A. Bradley, Luis F. Veiros, Doris Pun, Emil Lobkovsky, Ivan Keresztes, Paul J. Chírik

Research output: Contribution to journalArticle

55 Scopus citations

Abstract

Treatment of the η95-bis(indenyl)zirconium sandwich complex, (η9-C9H5-1,3-(SiMe 3)2)(η5-C9H5-1,3- (SiMe3)2)Zr, with dialkyl ethers such as diethyl ether, CH3OR (R = Et, nBu, tBu), nBu 2O, or iPr2O resulted in facile C-O bond scission furnishing an η55-bis(indenyl)zirconium alkoxy hydride complex and free olefin. In cases where ethylene is formed, trapping by the zirconocene sandwich yields a rare example of a crystallographically characterized, base-free η5, η5-bis(indenyl)zirconium ethylene complex. Observation of normal, primary kinetic isotope effects in combination with rate studies and the stability of various model compounds support a mechanism involving rate-determining C-H activation to yield an η55- bis(indenyl)-zirconium alkyl hydride intermediate followed by rapid β-alkoxide elimination. For isolable η65- bis(indenyl)-zirconium THF compounds, thermolysis at 85 °C also resulted in C-O bond cleavage to yield the corresponding zirconacycle. Both mechanistic and computational studies again support a pathway involving haptotropic rearrangement to η55-bis(indenyl)zirconium intermediates that promote rate-determining C-H activation and ultimately C-O bond scission.

Original languageEnglish (US)
Pages (from-to)16600-16612
Number of pages13
JournalJournal of the American Chemical Society
Volume128
Issue number51
DOIs
StatePublished - Dec 27 2006
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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