Contrasting behaviour under pressure reveals the reasons for pyramidalization in tris(amido)uranium(III) and tris(arylthiolate) uranium(III) molecules

Price, Amy N, Berryman, Victoria ORCID: 0000-0003-0200-4788, Ochiai, Tatsumi, Shephard, Jacob J, Parsons, Simon, Kaltsoyannis, Nikolas and Arnold, Polly L (2022) Contrasting behaviour under pressure reveals the reasons for pyramidalization in tris(amido)uranium(III) and tris(arylthiolate) uranium(III) molecules. Nature Communications, 13 (1). 3931-.

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Official URL: http://dx.doi.org/10.1038/s41467-022-31550-7

Abstract

<jats:title>Abstract</jats:title><jats:p>A range of reasons has been suggested for why many low-coordinate complexes across the periodic table exhibit a geometry that is bent, rather a higher symmetry that would best separate the ligands. The dominating reason or reasons are still debated. Here we show that two pyramidal UX<jats:sub>3</jats:sub> molecules, in which X is a bulky anionic ligand, show opposite behaviour upon pressurisation in the solid state. UN″<jats:sub>3</jats:sub> (<jats:bold>UN3</jats:bold>, N″ = N(SiMe<jats:sub>3</jats:sub>)<jats:sub>2</jats:sub>) increases in pyramidalization between ambient pressure and 4.08 GPa, while U(SAr)<jats:sub>3</jats:sub> (<jats:bold>US3</jats:bold>, SAr = S-C<jats:sub>6</jats:sub>H<jats:sub>2</jats:sub>-<jats:sup>t</jats:sup>Bu<jats:sub>3</jats:sub>−2,4,6) undergoes pressure-induced planarization. This capacity for planarization enables the use of X-ray structural and computational analyses to explore the four hypotheses normally put forward for this pyramidalization. The pyramidality of <jats:bold>UN3</jats:bold>, which increases with pressure, is favoured by increased dipole and reduction in molecular volume, the two factors outweighing the slight increase in metal-ligand agostic interactions that would be formed if it was planar. The ambient pressure pyramidal geometry of <jats:bold>US3</jats:bold> is favoured by the induced dipole moment and agostic bond formation but these are weaker drivers than in <jats:bold>UN3</jats:bold>; the pressure-induced planarization of <jats:bold>US3</jats:bold> is promoted by the lower molecular volume of <jats:bold>US3</jats:bold> when it is planar compared to when it is pyramidal.</jats:p>

Item Type:	Article
Divisions:	Faculty of Science and Engineering > School of Physical Sciences
Depositing User:	Symplectic Admin
Date Deposited:	13 Jul 2022 10:28
Last Modified:	18 Jan 2023 20:56
DOI:	10.1038/s41467-022-31550-7
Related URLs:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3158374