Issue 3, 2023

Photoactivation of titanium-oxo cluster [Ti6O6(OR)6(O2CtBu)6]: mechanism, photoactivated structures, and onward reactivity with O2 to a peroxide complex

Abstract

The molecular titanium-oxo cluster [Ti6O6(OiPr)6(O2CtBu)6] (1) can be photoactivated by UV light, resulting in a deeply coloured mixed valent (photoreduced) Ti (III/IV) cluster, alongside alcohol and ketone (photooxidised) organic products. Mechanistic studies indicate that a two-electron (not free-radical) mechanism occurs in this process, which utilises the cluster structure to facilitate multielectron reactions. The photoreduced products [Ti6O6(OiPr)4(O2CtBu)6(sol)2], sol = iPrOH (2) or pyridine (3), can be isolated in good yield and are structurally characterized, each with two, uniquely arranged, antiferromagnetically coupled d-electrons. 2 and 3 undergo onward oxidation under air, with 3 cleanly transforming into peroxide complex, [Ti6O6(OiPr)4(O2CtBu)6(py)(O2)] (5). 5 reacts with isopropanol to regenerate the initial cluster (1) completing a closed cycle, and suggesting opportunities for the deployment of these easily made and tuneable clusters for sustainable photocatalytic processes using air and light. The redox reactivity described here is only possible in a cluster with multiple Ti sites, which can perform multi-electron processes and can adjust its shape to accommodate changes in electron density.

Graphical abstract: Photoactivation of titanium-oxo cluster [Ti6O6(OR)6(O2CtBu)6]: mechanism, photoactivated structures, and onward reactivity with O2 to a peroxide complex

Supplementary files

Article information

Article type
Edge Article
Submitted
12 Oct 2022
Accepted
06 Dec 2022
First published
07 Dec 2022
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2023,14, 675-683

Photoactivation of titanium-oxo cluster [Ti6O6(OR)6(O2CtBu)6]: mechanism, photoactivated structures, and onward reactivity with O2 to a peroxide complex

S. E. Brown, I. Mantaloufa, R. T. Andrews, T. J. Barnes, M. R. Lees, F. De Proft, A. V. Cunha and S. D. Pike, Chem. Sci., 2023, 14, 675 DOI: 10.1039/D2SC05671B

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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