Mechanistic study of the [(dpp-bian)Re(CO)3Br] electrochemical reduction using in situ EPR spectroscopy and computational chemistry

Pavel A. Abramov, Alexey A. Dmitriev, Kirill V. Kholin, Nina P. Gritsan, Marsil K. Kadirov, Artem L. Gushchin, Maxim N. Sokolov

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)

Abstract

The [(α-diimine)Re(CO)3(Hal)] complexes are able to act as efficient catalysts for electrochemical reduction of CO2 into energy-rich compounds. Among the α-diimine ligands, the 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-bian) attracted recently increased attention. Reaction of [Re(CO)5Br] with dpp-bian leads to formation of [(dpp-bian)Re(CO)3Br], which was isolated and characterized by XRD as solvent-free [(dpp-bian)Re(CO)3Br] (1), and two solventomorphs [(dpp-bian)Re(CO)3Br]·C6H5CH3 (1-C7H8) and [(dpp-bian)Re(CO)3Br]·0.5CH3CN (1-0.5CH3CN). Electrochemical reduction of 1 in DMF and CH3CN has been studied using CV and in situ EPR spectroelectrochemistry. According to the experimental results, complex 1 undergoes in DMF multistep reduction via a number of intermediates, two of which were detected using in situ EPR spectroscopy. A careful theoretical analysis of the multistep reduction mechanism including calculations of the thermodynamics of elementary reactions and electronic structures of proposed intermediates has been performed. General scheme of the electrochemical reduction, which is essentially ligand-centered, has been proposed and supported by full-electron DFT calculations with scalar relativistic DKH2 and ZORA Hamiltonians.

Original languageEnglish
Pages (from-to)526-534
Number of pages9
JournalElectrochimica Acta
Volume270
DOIs
Publication statusPublished - 20 Apr 2018

Keywords

  • Cyclic voltammetry
  • Electrochemical reduction
  • Electronic structure of intermediates
  • Full-electron relativistic DFT
  • In situ EPR
  • Thermodynamics of elementary reactions
  • EXCITED-STATE
  • TRANSITION-METAL-COMPLEXES
  • PHOTOCATALYTIC REDUCTION
  • NON-INNOCENT LIGAND
  • CORRELATION-ENERGY
  • REDOX-ACTIVE LIGANDS
  • GENERALIZED GRADIENT APPROXIMATION
  • ZETA VALENCE QUALITY
  • CARBON-DIOXIDE
  • GAUSSIAN-BASIS SETS

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