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Nemirovich T, Young B, Brezina K, Mason PE, Seidel R, Stemer D, Winter B, Jungwirth P, Bradforth SE, Schewe HC. Stability and Reactivity of Aromatic Radical Anions in Solution with Relevance to Birch Reduction. J Am Chem Soc 2024; 146:8043-8057. [PMID: 38363862 PMCID: PMC10979400 DOI: 10.1021/jacs.3c11655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 01/17/2024] [Accepted: 01/18/2024] [Indexed: 02/18/2024]
Abstract
We investigate the electronic structure of aromatic radical anions in the solution phase employing a combination of liquid-jet (LJ) photoelectron (PE) spectroscopy measurements and electronic structure calculations. By using recently developed protocols, we accurately determine the vertical ionization energies of valence electrons of both the solvent and the solute molecules. In particular, we first characterize the pure solvent of tetrahydrofuran (THF) by LJ-PE measurements in conjunction with ab initio molecular dynamics simulations and G0W0 calculations. Next, we determine the electronic structure of neutral naphthalene (Np) and benzophenone (Bp) as well as their radical anion counterparts Np- and Bp- in THF. Wherever feasible, we performed orbital assignments of the measured PE features of the aromatic radical anions, with comparisons to UV-vis absorption spectra of the corresponding neutral molecules being instrumental in rationalizing the assignments. Analysis of the electronic structure differences between the neutral species and their anionic counterparts provides understanding of the primarily electrostatic stabilization of the radical anions in solution. Finally, we obtain a very good agreement of the reduction potentials extracted from the present LJ-PES measurements of Np- and Bp- in THF with previous electrochemical data from cyclic voltammetry measurements. In this context, we discuss how the choice of solvent holds significant implications for optimizing conditions for the Birch reduction process, wherein aromatic radical anions play crucial roles as reactive intermediates.
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Affiliation(s)
- Tatiana Nemirovich
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Brandon Young
- Department
of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Krystof Brezina
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Philip E. Mason
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Robert Seidel
- Helmholtz-Zentrum
Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - Dominik Stemer
- Fritz-Haber-Institut
der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - Bernd Winter
- Fritz-Haber-Institut
der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - Pavel Jungwirth
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Stephen E. Bradforth
- Department
of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - H. Christian Schewe
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
- J.
Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech
Republic
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Nemirovich T, Kostal V, Copko J, Schewe HC, Boháčová S, Martinek T, Slanina T, Jungwirth P. Bridging Electrochemistry and Photoelectron Spectroscopy in the Context of Birch Reduction: Detachment Energies and Redox Potentials of Electron, Dielectron, and Benzene Radical Anion in Liquid Ammonia. J Am Chem Soc 2022; 144:22093-22100. [DOI: 10.1021/jacs.2c09478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tatiana Nemirovich
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 2, 166 10Prague 6, Czech Republic
| | - Vojtech Kostal
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 2, 166 10Prague 6, Czech Republic
| | - Jakub Copko
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 2, 166 10Prague 6, Czech Republic
| | - H. Christian Schewe
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 2, 166 10Prague 6, Czech Republic
| | - Soňa Boháčová
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 2, 166 10Prague 6, Czech Republic
| | - Tomas Martinek
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 2, 166 10Prague 6, Czech Republic
| | - Tomas Slanina
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 2, 166 10Prague 6, Czech Republic
| | - Pavel Jungwirth
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 2, 166 10Prague 6, Czech Republic
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Brezina K, Kostal V, Jungwirth P, Marsalek O. Electronic structure of the solvated benzene radical anion. J Chem Phys 2022; 156:014501. [PMID: 34998349 DOI: 10.1063/5.0076115] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The benzene radical anion is a molecular ion pertinent to several organic reactions, including the Birch reduction of benzene in liquid ammonia. The species exhibits a dynamic Jahn-Teller effect due to its open-shell nature and undergoes pseudorotation of its geometry. Here, we characterize the complex electronic structure of this condensed-phase system based on ab initio molecular dynamics simulations and GW calculations of the benzene radical anion solvated in liquid ammonia. Using detailed analysis of the molecular and electronic structure, we find that the spatial character of the excess electron of the solvated radical anion follows the underlying Jahn-Teller distortions of the molecular geometry. We decompose the electronic density of states to isolate the contribution of the solute and to examine the response of the solvent to its presence. Our findings show the correspondence between instantaneous molecular structure and spin density; provide important insights into the electronic stability of the species, revealing that it is, indeed, a bound state in the condensed phase; and offer electronic densities of states that aid in the interpretation of experimental photoelectron spectra.
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Affiliation(s)
- Krystof Brezina
- Charles University, Faculty of Mathematics and Physics, Ke Karlovu 3, 121 16 Prague 2, Czech Republic
| | - Vojtech Kostal
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 2, 16610 Prague 6, Czech Republic
| | - Pavel Jungwirth
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 2, 16610 Prague 6, Czech Republic
| | - Ondrej Marsalek
- Charles University, Faculty of Mathematics and Physics, Ke Karlovu 3, 121 16 Prague 2, Czech Republic
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