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, 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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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
Uncontrolled Keywords: 3402 Inorganic Chemistry, 34 Chemical Sciences, 2.1 Biological and endogenous factors, 2 Aetiology
Divisions: Faculty of Science and Engineering > School of Physical Sciences
Depositing User: Symplectic Admin
Date Deposited: 13 Jul 2022 10:28
Last Modified: 21 Jun 2024 13:10
DOI: 10.1038/s41467-022-31550-7
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3158374