| Autor: |
Manbeck GF; Chemistry Division, Brookhaven National Laboratory, Upton, NY 11973-5000, USA. gmanbeck@bnl.gov mzertem@bnl.gov fujita@bnl.gov., Garg K, Shimoda T, Szalda DJ, Ertem MZ, Muckerman JT, Fujita E |
| Jazyk: |
angličtina |
| Zdroj: |
Faraday discussions [Faraday Discuss] 2017 Jun 02; Vol. 198, pp. 301-317. |
| DOI: |
10.1039/c6fd00223d |
| Abstrakt: |
We prepared electron-rich derivatives of [Ir(tpy)(ppy)Cl] + with modification of the bidentate (ppy) or tridentate (tpy) ligands in an attempt to increase the reactivity for CO 2 reduction and the ability to transfer hydrides (hydricity). Density functional theory (DFT) calculations reveal that complexes with dimethyl-substituted ppy have similar hydricities to the non-substituted parent complex, and photocatalytic CO 2 reduction studies show selective CO formation. Substitution of tpy by bis(benzimidazole)-phenyl or -pyridine (L3 and L4, respectively) induces changes in the physical properties that are much more pronounced than from the addition of methyl groups to ppy. Theoretical data predict [Ir(L3)(ppy)(H)] as the strongest hydride donor among complexes studied in this work, but [Ir(L3)(ppy)(NCCH 3 )] + cannot be reduced photochemically because the excited state reduction potential is only 0.52 V due to the negative ground state potential of -1.91 V. The excited state of [Ir(L4)(ppy)(NCCH 3 )] 2+ is the strongest oxidant among complexes studied in this work and the singly-reduced species is formed readily upon photolysis in the presence of tertiary amines. Both [Ir(L3)(ppy)(NCCH 3 )] + and [Ir(L4)(ppy)(NCCH 3 )] 2+ exhibit electrocatalytic current for CO 2 reduction. While a significantly greater overpotential is needed for the L3 complex, a small amount of formate (5-10%) generation in addition to CO was observed as predicted by the DFT calculations. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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