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

作者：Abramov Pavel A^*; Dmitriev Alexey A; Kholin Kirill V; Gritsan Nina P^*; Kadirov Marsil K; Gushchin Artem L; Sokolov Maxim N

来源：Electrochimica Acta, 2018, 270: 526-534.

DOI：10.1016/j.electacta.2018.03.111

• Electrochemical reduction
• Cyclic voltammetry
• In situ EPR
• Full-electron relativistic DFT
• Thermodynamics of elementary reactions
• Electronic structure of intermediates

The [(alpha-diimine)Re(CO)(3)(Hal)] complexes are able to act as efficient catalysts for electrochemical reduction of CO2 into energy-rich compounds. Among the alpha-diimine ligands, the 1,2-bis[(2,6-diisopropylphenyl)imino] acenaphthene (dpp-bian) attracted recently increased attention. Reaction of [Re(CO)(5)Br] with dpp-bian leads to formation of [(dpp-bian)Re(CO)(3)Br], which was isolated and characterized by XRD as solvent-free [(dpp-bian)Re(CO)(3)Br] (1), and two solventomorphs [(dpp-bian)Re(CO)(3)Br]center dot C6H5CH3 (1-C7H8) and [(dpp-bian)Re(CO)(3)Br]center dot 0.5CH(3)CN (1-0.5CH(3)CN). 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.

• 出版日期2018-4-20