Electrochemical reduction of CO{sub 2} catalyzed by dinuclear palladium complex containing bridging hexaphosphine ligand: Evidence for cooperativity
- National Renewable Energy Lab., Golden, CO (United States)
The complexes [Pd{sub 2}(CH{sub 3}CN){sub 2}(eHTP)](BF{sub 4}){sub 4} and [Pd{sub 2}(PEt{sub 3}){sub 2}(eHTP)](BF{sub 4}){sub 4} (where eHTP is bis(bis((diethylphosphino)ethyl)phosphino))methane, (Et{sub 2} PCH{sub 2}CH{sub 2}){sub 2}PCH{sub 2}P(CH{sub 2}CH{sub 2}PEt{sub 2}){sub 2} were prepared and characterized. [Pd{sub 2}(CH{sub 3}CN){sub 2} (eHTP)](BF{sub 4}){sub 4} catalyzes the electrochemical reduction of CO{sub 2} to CO in acidic dimethylformamide solutions. The rate of this reaction exhibits a biphasic dependence on acid, with-a first-order dependence at low acid concentrations and zero-order dependence at acid concentrations greater than 0.06 M. At high acid concentrations the rate-limiting step is first order in catalyst and first order in CO{sub 2}. When compared to the kinetic properties of previously studied mononuclear complexes, these data suggest both palladium atoms are involved in CO{sub 2} reduction. The closely related complex [Pd{sub 2}(PEt{sub 3}){sub 2}(eHTP)](BF{sub 4}){sub 4} undergoes two reversible two-electron reductions. The mixed-valence intermediate resulting from the first two-electron reduction is unstable and undergoes rapid decomposition. 34 refs., 7 figs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 136089
- Journal Information:
- Organometallics, Journal Name: Organometallics Journal Issue: 10 Vol. 14; ISSN ORGND7; ISSN 0276-7333
- Country of Publication:
- United States
- Language:
- English
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