Characterization of the alkali metal oxalates (MC2O4−) and their formation by CO2 reduction via the alkali metal carbonites (MCO2−)

Joakim S. Jestilä; Joanna K. Denton; Evan H. Perez; Thien Khuu; Edoardo Aprà; Sotiris S. Xantheas; Mark A. Johnson; Einar Uggerud

doi:10.1039/D0CP00547A

Characterization of the alkali metal oxalates (MC₂O₄⁻) and their formation by CO₂ reduction via the alkali metal carbonites (MCO₂⁻)†

Joakim S. Jestilä,

^a Joanna K. Denton,

^b Evan H. Perez,^b Thien Khuu,

^b Edoardo Aprà,

^c Sotiris S. Xantheas,

^de Mark A. Johnson

^b and Einar Uggerud

*^a

Author affiliations

* Corresponding authors

^a Department of Chemistry and Hylleraas Centre for Quantum Molecular Sciences, University of Oslo, P.O. Box 1033, Blindern, Oslo N-0135, Norway
E-mail: einar.uggerud@kjemi.uio.no

^b Sterling Chemistry Laboratory, Yale University, New Haven, Connecticut 06520, USA

^c Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, USA

^d Advanced Computing, Mathematics and Data Division, Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, MS K1-83, Richland, Washington, USA

^e Department of Chemistry, University of Washington, Seattle, Washington 98195, USA

Abstract

The reduction of carbon dioxide to oxalate has been studied by experimental Collisionally Induced Dissociation (CID) and vibrational characterization of the alkali metal oxalates, supplemented by theoretical electronic structure calculations. The critical step in the reductive process is the coordination of CO₂ to an alkali metal anion, forming a metal carbonite MCO₂⁻ able to subsequently receive a second CO₂ molecule. While the energetic demand for these reactions is generally low, we find that the degree of activation of CO₂ in terms of charge transfer and transition state energies is the highest for lithium and systematically decreases down the group (M = Li–Cs). This is correlated to the strength of the binding interaction between the alkali metal and CO₂, which can be related to the structure of the oxalate moiety within the product metal complexes evolving from a planar to a staggered conformer with increasing atomic number of the interacting metal. Similar structural changes are observed for crystalline alkali metal oxalates, although the C₂O₄²⁻ moiety is in general more planar in these, a fact that is attributed to the increased number of interacting alkali metal cations compared to the gas-phase ions.

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Article information

DOI: https://doi.org/10.1039/D0CP00547A
Article type: Paper
Submitted: 31 Jan 2020
Accepted: 10 Mar 2020
First published: 13 Mar 2020

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Phys. Chem. Chem. Phys., 2020,22, 7460-7473

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Characterization of the alkali metal oxalates (MC₂O₄⁻) and their formation by CO₂ reduction via the alkali metal carbonites (MCO₂⁻)

J. S. Jestilä, J. K. Denton, E. H. Perez, T. Khuu, E. Aprà, S. S. Xantheas, M. A. Johnson and E. Uggerud, Phys. Chem. Chem. Phys., 2020, 22, 7460 DOI: 10.1039/D0CP00547A

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