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Bond Character and Conformational Equilibration of Ethylene- and Tetrafluoroethylenerhodium Complexes from Nuclear Magnetic Resonance Spectra

Cramer, Richard and Kline, Jules B. and Roberts, John D. (1969) Bond Character and Conformational Equilibration of Ethylene- and Tetrafluoroethylenerhodium Complexes from Nuclear Magnetic Resonance Spectra. Journal of the American Chemical Society, 91 (10). pp. 2519-2524. ISSN 0002-7863. doi:10.1021/ja01038a021.

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The nuclear magnetic resonance spectra of π-cyclopentadienyldiethylenerhodium (l), π-cyclopentadienylethylene(su1fur dioxide)rhodium (2), and π-cyclopentadienylethylenetetrafluoroethylenerhodium (3) have been analyzed in terms of chemical shifts and coupling constants. There is relatively small difference between the proton-proton couplings, but a larger difference between fluorine-fluorine couplings of the coordinated and free alkenes, which suggests that coordination with rhodium produces a sizable change in hybridization of tetrafluoroethylene carbons. "π-Alkene complex" may be a misnomer for 3. The barrier to rotation of the ethylenes in 1 about the carbon-rhodium bonds has been reinvestigated and found to have an activation energy of 15.0 ± 0.2 kcal/mol instead of about 6 kcal as previously reported. The E, value for rotation of the ethylene in 2 is substantially less, 12.2 ± 0.8 kcal/mol, while that of 3 is somewhat more than for 2, 13.6 ± 0.6 kcal/mol. Rotation of coordinated tetrafluoroethylene does not appear to be detectable up to 100º, the point where 3 begins to decompose.

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Additional Information:© 1969 American Chemical Society. Received November 4, 1968. The part of this research carried on at the California Institute of Technology was supported by the National Science Foundation. Participant in the Undergraduate Research Program of the National Science Foundation.
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NSF Undergraduate Research ProgramUNSPECIFIED
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Caltech Gates and Crellin Laboratories3717
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Official Citation:Bond character and conformational equilibration of ethylene- and tetrafluoroethylenerhodium complexes from nuclear magnetic resonance spectra Richard Cramer, Jules B. Kline, and John D. Roberts Journal of the American Chemical Society 1969 91 (10), 2519-2524 DOI: 10.1021/ja01038a021
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:61076
Deposited By: Ruth Sustaita
Deposited On:14 Oct 2015 21:49
Last Modified:10 Nov 2021 22:44

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