Excitation Wavelength Dependent O2 Release from Copper(II)–Superoxide 
Compounds: Laser Flash-Photolysis Experiments and Theoretical Studies

Saracini, Claudio; Liakos, Dimitrios G.; Zapata Rivera, Jhon E.; Neese, Frank; Meyer, Gerald J.; Karlin, Kenneth D.

doi:10.1021/ja4115314

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Excitation Wavelength Dependent O₂ Release from Copper(II)–Superoxide Compounds: Laser Flash-Photolysis Experiments and Theoretical Studies

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Liakos, Dimitrios G.
Research Department Neese, Max Planck Institute for Chemical Energy Conversion, Max Planck Society;

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Neese, Frank
Research Department Neese, Max Planck Institute for Chemical Energy Conversion, Max Planck Society;

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Citation

Saracini, C., Liakos, D. G., Zapata Rivera, J. E., Neese, F., Meyer, G. J., & Karlin, K. D. (2014). Excitation Wavelength Dependent O₂ Release from Copper(II)–Superoxide Compounds: Laser Flash-Photolysis Experiments and Theoretical Studies. Journal of the American Chemical Society, 136(4), 1260-1263. doi:10.1021/ja4115314.

Cite as: https://hdl.handle.net/21.11116/0000-0007-A2A8-4

Abstract

Irradiation of the copper(II)–superoxide synthetic complexes [(TMG₃tren)Cu^II(O₂)]⁺ (1) and [(PV-TMPA)Cu^II(O₂)]⁺ (2) with visible light resulted in direct photogeneration of O₂ gas at low temperature (from −40 °C to −70 °C for 1 and from −125 to −135 °C for 2) in 2-methyltetrahydrofuran (MeTHF) solvent. The yield of O₂ release was wavelength dependent: λ_exc = 436 nm, ϕ = 0.29 (for 1), ϕ = 0.11 (for 2), and λ_exc = 683 nm, ϕ = 0.035 (for 1), ϕ = 0.078 (for 2), which was followed by fast O₂-recombination with [(TMG₃tren)Cu^I]⁺ (3) and [(PV-TMPA)Cu^I]⁺ (4). Enthalpic barriers for O₂ rebinding to the copper(I) center (∼10 kJ mol^–1) and for O₂ dissociation from the superoxide compound 1 (45 kJ mol^–1) were determined. TD-DFT studies, carried out for 1, support the experimental results confirming the dissociative character of the excited states formed upon blue- or red-light laser excitation.