Long-Lived Charge Transfer States of Nickel(II) Aryl Halide Complexes Facilitate Bimolecular Photoinduced Electron Transfer
Published in Journal of the American Chemical Society, 2018
Recommended citation: Shields, Benjamin J.; Kudisch, Bryan; Scholes, Gregory, D.; Doyle, Abigail G. “Long-Lived Charge Transfer States of Nickel(II) Aryl Halide Complexes Facilitate Bimolecular Photoinduced Electron Transfer” J. Am. Chem. Soc., 2018, 140, 3035–3039. https://pubs.acs.org/doi/10.1021/jacs.7b13281
Here we investigate the photophysics and photochemistry of Ni(II) aryl halide complexes common to cross-coupling and Ni/photoredox reactions. Computational and ultrafast spectroscopic studies reveal that these complexes feature long-lived excited states, implicating Ni as an underexplored alternative to precious metal photocatalysts. Moreover, we show that 3MLCT Ni(II) engages in bimolecular electron transfer with ground-state Ni(II), which enables access to Ni(III) in the absence of external oxidants or photoredox catalysts. As such, it is possible to facilitate Ni-catalyzed C–O bond formation solely by visible light irradiation, thus representing an alternative strategy for catalyst activation in Ni cross-coupling reactions.