TY - JOUR

T1 - Mechanistic study of the [(dpp-bian)Re(CO)3Br] electrochemical reduction using in situ EPR spectroscopy and computational chemistry

AU - Abramov, Pavel A.

AU - Dmitriev, Alexey A.

AU - Kholin, Kirill V.

AU - Gritsan, Nina P.

AU - Kadirov, Marsil K.

AU - Gushchin, Artem L.

AU - Sokolov, Maxim N.

N1 - Publisher Copyright: © 2018 Elsevier Ltd

PY - 2018/4/20

Y1 - 2018/4/20

N2 - 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.

AB - 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.

KW - Cyclic voltammetry

KW - Electrochemical reduction

KW - Electronic structure of intermediates

KW - Full-electron relativistic DFT

KW - In situ EPR

KW - Thermodynamics of elementary reactions

KW - EXCITED-STATE

KW - TRANSITION-METAL-COMPLEXES

KW - PHOTOCATALYTIC REDUCTION

KW - NON-INNOCENT LIGAND

KW - CORRELATION-ENERGY

KW - REDOX-ACTIVE LIGANDS

KW - GENERALIZED GRADIENT APPROXIMATION

KW - ZETA VALENCE QUALITY

KW - CARBON-DIOXIDE

KW - GAUSSIAN-BASIS SETS

UR - http://www.scopus.com/inward/record.url?scp=85044439455&partnerID=8YFLogxK

U2 - 10.1016/j.electacta.2018.03.111

DO - 10.1016/j.electacta.2018.03.111

M3 - Article

AN - SCOPUS:85044439455

VL - 270

SP - 526

EP - 534

JO - Electrochimica Acta

JF - Electrochimica Acta

SN - 0013-4686

ER -