Activation of Carbon-Hydrogen Bonds by Some Derivatives of Bis(cyclopentadienyl)zirconium(IV)

Author: Erwin, David Keith

Year: 1979

Degree: Dissertation (Ph.D.)

Advisor: Bercaw, John E.

Committee Member: Unknown, Unknown

Option: Chemistry

DOI: 10.7907/h512-mv70

Abstract

In the presence of D2, bis{pentamethylcyclopentadienyl)zirconium(IV) dihydride [Formula. See abstract in scanned thesis for details] shows deuterium exchange with both the hydride and the thirty ring methyl hydrogen positions. At -78°C only the hydride ligands exchange with D2 to yield H2, HD, and D2. At temperatures above 5O°C the rate of D2 incorporation (as determined by 1H-nmr) into the ring methyl hydrogens is found to be first order in [Zr] and independent of D2 pressure. Other bis(alkyltetramethylcyclopentadienyl)zirconium{IV) dihydrides show regioselective D2 exchange. A mechanism for this intramolecular carbon-hydrogen activation and consistent with these data is presented involving a facile and reversible metal-to-ring hydride transfer. Results for solvent activation are also presented.

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