C-D(0) (D(0) = pi-donor, F) Cleavage in H(2)C=CH(D(0)) by (Cp(2)ZrHCl)(n): mechanism, agostic fluorines, and a carbene of Zr(IV). |
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| Authors: | L A Watson D V Yandulov K G Caulton |
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| Institution: | Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102, USA. |
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| Abstract: | Consistent with the C-O cleavage behavior of vinyl ethers, vinyl fluoride reacts with Cp(2)ZrHCl to give Cp(2)ZrFCl and C(2)H(4) as primary products. DFT (B3PW91) calculations show this reaction to be highly exoenergetic (-55 kcal/mol), and reveal a sigma-bond metathesis mechanism to be unfavorable compared to a Zr-H addition across the C=C bond, with regiochemistry placing F on C(beta) of the resulting fluoroethyl ligand. beta-F elimination (onto Zr) then completes the reaction. There is no eta(2)-olefin intermediate on the reaction path. DFT calculations seeking the energy and structure of the two carbenes Cp(2)ZrHClCF(CH(3))] and Cp(2)ZrFClCH(CH(3))] are also described. |
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