New Rh <sub>2</sub> (II,II) Architecture for the Catalytic Reduction of H <sup>+</sup> [electronic resource].
- Washington, D.C. : United States. Dept. of Energy. Office of Basic Energy Sciences, 2015.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy
- Physical Description:
- pages 10,042-10,048 : digital, PDF file
- Additional Creators:
- Ohio State University, United States. Department of Energy. Office of Basic Energy Sciences, and United States. Department of Energy. Office of Scientific and Technical Information
- Restrictions on Access:
- Free-to-read Unrestricted online access
- Formamidinate-bridged Rh2II,II complexes containing diimine ligands of the formula cis-[Rh2II,II(μ-DTolF)2(NN)2]2+ (Rh2-NN2), where DTolF = p-ditolylformamidinate and NN = dppn (benzo[i]dipyrido[3,2-a:2',3'-h]quinoxaline), dppz (dipyrido[3,2-a:2',3'-c]phenazine), and phen (1,10-phenanthroline), electrocatalytically reduce H+ to H2 in DMF solutions containing CH3COOH at a glassy carbon electrode. Cathodic scans in the absence of acid display a RhIII,II/II,II reduction at -0.90 V vs Fc+/Fc followed by NN0/– reduction at -1.13, -1.36, and -1.65 V for Rh2-dppn2, Rh2-dppz2, and Rh2-phen2, respectively. Upon the addition of acid, Rh2-dppn2 and Rh2-dppz2 undergo reduction–protonation–reduction at each pyrazine-containing NN ligand prior to the Rh2II,II/II,I reduction. The Rh2II,I species is thus protonated at one of the metal centers, resulting in the formation of the corresponding Rh2II,III-hydride. In the case of Rh2-phen2, the reduction of the phen ligand is followed by intramolecular electron transfer to the Rh2II,II core in the presence of protons to form a Rh2II,III-hydride species. Further reduction and protonation at the Rh2 core for all three complexes rapidly catalyzes H2 formation with varied calculated turnover frequencies (TOF) and overpotential values (η): 2.6 × 104 s–1 and 0.56 V for Rh2-dppn, 2.8 × 104 s–1 and 0.50 V for Rh2-dppz2, and 5.9 × 104 s–1 and 0.64 V for Rh2-phen2. Bulk electrolysis confirmed H2 formation, and further CH3COOH addition regenerates H2 production, attesting to the robust nature of the architecture. The cis-[Rh2II,II(μ-DTolF)2(NN)2]2+ architecture benefits by combining electron-rich formamidinate bridges, a redox-active Rh2II,II core, and electron-accepting NN diimine ligands to allow for the electrocatalysis of H+ substrate to H2 fuel.
- Report Numbers:
- E 1.99:1430201
- Other Subject(s):
- Published through SciTech Connect.
Inorganic Chemistry 54 20 ISSN 0020-1669 AM
Travis A. White; Suzanne E. Witt; Zhanyong Li; Kim R. Dunbar; Claudia Turro.
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