Phosphine substitution in (.eta.5-cyclopentadienyl)bis(triphenylphosphine)cobalt(I) [electronic resource] : evidence for a dissociative mechanism.
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Online Access |
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| Format: | Government Document Electronic eBook |
| Language: | English |
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Washington, D.C. : Oak Ridge, Tenn. :
United States. Department of Energy. Office of Basic Energy Sciences ; distributed by the Office of Scientific and Technical Information, U.S. Department of Energy,
1981.
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| Abstract: | The substitution of trimethylphosphine for triphenylphosphine in (η<sup>5</sup>-cyclopentadienyl)bis(triphenylphosphine)cobalt(I) (1) to form (η<sup>5</sup>-cyclopentadienyl)(trimethylphosphine)(triphenylphosphine)cobalt(I) was studied at -60°C in an NMR spectrometer. Kinetic measurements show the process to be first order in 1 and zero order in PMe<sub>3</sub>; added PPh<sub>3</sub> strongly inhibits the reaction rate. This information indicates the reaction proceeds by rapid reversible phosphine dissociation through the unsaturated CpCo(PPh<sub>3</sub>) intermediate. The rate for generation of that intermediate, k<sub>1</sub>, is 1.15 x 10<sup>-3</sup>s<sup>-1</sup> while the ratio of rate constant k<sub>2</sub> (for conversion of intermediate to products) to k<sub>-1</sub> (return to starting materials) is 4 at -60°C. Possible structures for CpCo(L) are also discussed in light of recent indications that the linear structure has a triplet ground state. |
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| Item Description: | Published through SciTech Connect. 03/01/1981. "lbl--11160" Journal of the American Chemical Society 103 6 ISSN 0002-7863 FT. Bergman, Robert G.; Janowicz, Andrew H.; Bryndza, Henry E. |
| Physical Description: | p. 1516-1518 : digital, PDF file. |