Issue 5, 2024

What is the nature of the uranium(iii)–arene bond?

Abstract

Complexes of the form [U(η6-arene)(BH4)3] where arene = C6H6; C6H5Me; C6H3-1,3,5-R3 (R = Et, iPr, tBu, Ph); C6Me6; and triphenylene (C6H4)3 were investigated towards an understanding of the nature of the uranium–arene interaction. Density functional theory (DFT) shows the interaction energy reflects the interplay between higher energy electron rich π-systems which drive electrostatic contributions, and lower energy electron poor π-systems which give rise to larger orbital contributions. The interaction is weak in all cases, which is consistent with the picture that emerges from a topological analysis of the electron density where metrics indicative of covalency show limited dependence on the nature of the ligand – the interaction is predominantly electrostatic in nature. Complete active space natural orbital analyses reveal low occupancy U–arene π-bonding interactions dominate in all cases, while δ-bonding interactions are only found with high-symmetry and electron-rich C6Me6. Finally, both DFT and multireference calculations on a reduced, formally U(II), congener, [U(C6Me6)(BH4)3], suggests the electronic structure (S = 1 or 2), and hence metal oxidation state, of such a species cannot be deduced from structural features such as arene distortion alone. We show that arene geometry strongly depends on the spin-state of the complex, but that in both spin-states the complex is best described as U(III) with an arene-centred radical.

Graphical abstract: What is the nature of the uranium(iii)–arene bond?

Supplementary files

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Article information

Article type
Edge Article
Submitted
06 Sep 2023
Accepted
14 Dez 2023
First published
14 Dez 2023
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., 2024,15, 1810-1819

What is the nature of the uranium(III)–arene bond?

S. R. Chowdhury, C. A. P. Goodwin and B. Vlaisavljevich, Chem. Sci., 2024, 15, 1810 DOI: 10.1039/D3SC04715F

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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