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.
| Original language | English |
|---|---|
| Pages (from-to) | 675-683 |
| Number of pages | 9 |
| Journal | Chemical Science |
| Volume | 14 |
| Issue number | 3 |
| DOIs | |
| State | Published - Dec 7 2022 |
| Externally published | Yes |
Funding
SDP and TJB thank the Royal Society for their generous support of a Royal Society University Research Fellowship (URF\R1\191458). We thank the EPSRC for studentship for SEB through a Doctoral Training Partnership (DTP) grant. IM and TJB are grateful for support from the Warwick CDT in Analytical Science. Thanks to Dr David Walker, Dr Ivan Prokes and Dr Lijiang Song for technical support with X-ray crystallography, variable temperature NMR spectroscopy and ESI-mass spectrometry respectively. Ana V. Cunha thanks S. Dolas (SURF, NL) for allowing us to perform calculations on the experimental AMD platform kleurplaat maintained and operated by SURF Open Innovation Lab. FDP wishes to acknowledge the Vrije Universiteit Brussel (VUB) for the support to his research group through a strategic research program. FDP and AVC also thanks the Research Foundation Flanders (FWO) for support through a research grant (G024019N).