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Alkyl Rearrangement Processes in Organozirconium Complexes. Observation of Internal Alkyl Complexes during Hydrozirconation

Chirik, Paul J. and Day, Michael W. and Labinger, Jay A. and Bercaw, John E. (1999) Alkyl Rearrangement Processes in Organozirconium Complexes. Observation of Internal Alkyl Complexes during Hydrozirconation. Journal of the American Chemical Society, 121 (44). pp. 10308-10317. ISSN 0002-7863. https://resolver.caltech.edu/CaltechAUTHORS:20180413-134041553

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Abstract

Isotopically labeled alkyl zirconocene complexes of the form (CpR_n)_2Zr(CH_2CDR‘_2)(X) (CpR_n = alkyl-substituted cyclopentadienyl; R‘ = H, alkyl group; X = H, D, Me) undergo isomerization of the alkyl ligand as well as exchange with free olefin in solution under ambient conditions. Increasing the substitution on the Cp ring results in slower isomerization reactions, but these steric effects are small. In contrast, changing X has a very large effect on the rate of isomerization. Pure σ-bonding ligands such as methyl and hydride promote rapid isomerization, whereas π-donor ligands inhibit β-H elimination and hence alkyl isomerization. For (η^5-C_5H_5)2Zr(R)(Cl), internal alkyl complexes have been observed for the first time. The rate of isomerization depends on the length of the alkyl group:  longer alkyl chains (heptyl, hexyl) isomerize faster than shorter chains (butyl). The transient intermediate species have been identified by a combination of isotopic labeling and ^1H, ^2H, and ^(13)C NMR experiments. The solid-state structure of the zirconocene cyclopentyl chloride complex, Cp_2Zr(cyclo-C_5H_9)(Cl), has been determined by X-ray diffraction.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://dx.doi.org/10.1021/ja9912022DOIArticle
https://pubs.acs.org/doi/suppl/10.1021/ja9912022PublisherSupporting Information
ORCID:
AuthorORCID
Labinger, Jay A.0000-0002-1942-9232
Additional Information:© 1999 American Chemical Society. ReceiVed April 15, 1999. This work has been supported by the U.S. DOE Office of Basic Energy Sciences (Grant No. DE-FG03-85ER13431) and Exxon Chemicals America.
Funders:
Funding AgencyGrant Number
Department of Energy (DOE)DE-FG03-85ER13431
Exxon Chemicals AmericaUNSPECIFIED
Issue or Number:44
Record Number:CaltechAUTHORS:20180413-134041553
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20180413-134041553
Official Citation:Alkyl Rearrangement Processes in Organozirconium Complexes. Observation of Internal Alkyl Complexes during Hydrozirconation Paul J. Chirik, Michael W. Day, Jay A. Labinger, and John E. Bercaw Journal of the American Chemical Society 1999 121 (44), 10308-10317 DOI: 10.1021/ja9912022
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:85841
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:13 Apr 2018 20:51
Last Modified:03 Oct 2019 19:36

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