Red-Light-Active N,C,N-Pincer Bismuthinidene: Excited State Dynamics and Mechanism of Oxidative Addition into Aryl Iodides

Stamoulis A, Mato M, Bruzzese PC, Leutzsch M, Cadranel A, Gil-Sepulcre M, Neese F, Cornella J (2025)

Publication Type: Journal article

Publication year: 2025

Journal

Journal of the American Chemical Society American Chemical Society

DOI: 10.1021/jacs.4c16815

Abstract

Despite the progress made in the field of synthetic organic photocatalysis over the past decade, the use of higher wavelengths, especially those in the deep-red portion of the electromagnetic spectrum, remains comparatively rare. We have previously disclosed that a well-defined N,C,N-pincer bismuthinidene (1a) can undergo formal oxidative addition into a wide range of aryl electrophiles upon absorption of low-energy red light. In this study, we map out the photophysical dynamics of 1a and glean insights into the nature of the excited state responsible for the activation of aryl electrophiles. Transient absorption and emission techniques reveal that, upon irradiation with red light, the complex undergoes a direct S0 → S1 metal-to-ligand charge transfer (MLCT) transition, followed by rapid intersystem crossing (ISC) to a highly reducing emissive triplet state (−2.61 V vs Fc+/0 in MeCN). The low dissipative losses incurred during ISC (∼6% of the incident light energy) help rationalize the ability of the bismuthinidene to convert low-energy light into useful chemical energy. Spectroelectrochemical and computational data support a charge-separated excited-state structure with radical-anion character on the ligand and radical-cation character on bismuth. Kinetic studies and competition experiments afford insights into the mechanism of oxidative addition into aryl iodides; concerted and inner-sphere processes from the triplet excited state are ruled out, with the data strongly supporting a pathway that proceeds via outer-sphere dissociative electron transfer.

Authors with CRIS profile

Alejandro Cadranel

Involved external institutions

Max-Planck-Institut für Chemische Energiekonversion (MPI CEC) / Max-Planck-Institute for Chemical Energy Conversion DE Germany (DE) Max-Planck-Institut für Kohlenforschung (MPI KoFo) / Max Planck Institute for Coal Research DE Germany (DE) Universidad de Buenos Aires (UBA) / University of Buenos Aires AR Argentina (AR)

How to cite

APA:

Stamoulis, A., Mato, M., Bruzzese, P.C., Leutzsch, M., Cadranel, A., Gil-Sepulcre, M.,... Cornella, J. (2025). Red-Light-Active N,C,N-Pincer Bismuthinidene: Excited State Dynamics and Mechanism of Oxidative Addition into Aryl Iodides. Journal of the American Chemical Society. https://doi.org/10.1021/jacs.4c16815

MLA:

Stamoulis, Alexios, et al. "Red-Light-Active N,C,N-Pincer Bismuthinidene: Excited State Dynamics and Mechanism of Oxidative Addition into Aryl Iodides." Journal of the American Chemical Society (2025).

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