Mechanistic comparisons on Ru and Fe carbene-supported complexes for electrocatalytic CO2 reduction
Sergio Gonell Gómez a b, Julio Lloret-Fillol a, Alexander J. M. Miller b
a Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, 43007 Tarragona, Spain
b Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
Proceedings of International Conference on Frontiers in Electrocatalytic Transformations (INTERECT)
València, Spain, 2021 November 22nd - 23rd
Organizers: Elena Mas Marzá and Ward van der Stam
Contributed talk, Sergio Gonell Gómez, presentation 034
Publication date: 10th November 2021

The electrochemical reduction of CO2 is a challenging reaction of interest from a fundamental
perspective and as a candidate for converting an environmentally harmful gas into a valuable fuel.
Application in large scale of this reaction will likely require the use of catalysts based on cheap and
abundant metals. Organometallic ruthenium complexes bearing a 2,2':6',2''-terpyridine paired with a
bidentate ligand containing mixed pyridine-N-heterocyclic carbene are well established
electrocatalysts for CO2 reduction to CO (Figure 1).[1] We recently unraveled the mechanism for this
system, and we proved that the two geometrical isomers resulting from the asymmetry of the bis-
chelating ligand have completely different behavior in the elementary steps of the catalytic cycle, as a
consequence the trans effect provided by the strongly donating NHC donor.[2,3] Now in this
contribution, we will discuss the synthesis of the iron analogues, as well as the mechanism of this new
family of electrocatalysts in CO2 reduction.[4] A combination of NMR spectroscopy, cyclic
voltammetry, and spectroelectrochemical infrared spectroscopy have established similarities and
differences between the catalytic cycle performed by iron and ruthenium complexes.

[1] Z. Chen, C. Chen, D. R. Weinberg, P. Kang, J. J. Concepcion, D. P. Harrison, M. S. Brookhart, T. J.
Meyer, Chem. Commun. 2011, 47, 12607–12609. [2] S. Gonell, M. D. Massey, I. P. Moseley, C. K. Schauer, J. T. Muckerman, A. J. M. Miller, J. Am. Chem.
Soc. 2019, 141, 6658–6671. [3] S. Gonell, E. A. Assaf, K. D. Duffee, C. K. Schauer, A. J. M. Miller, J. Am. Chem. Soc. 2020, 142,
8980–8999. [4] S. Gonell, J. Lloret-Fillol, A. J. M. Miller, ACS Catal. 2021, 11, 615–626.

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