Covalent bond shortening and distortion induced by pressurization of thorium, uranium, and neptunium tetrakis aryloxides.

Shephard, Jacob J, Berryman, Victoria EJ ORCID: 0000-0003-0200-4788, Ochiai, Tatsumi, Walter, Olaf, Price, Amy N, Warren, Mark R, Arnold, Polly L, Kaltsoyannis, Nikolas and Parsons, Simon (2022) Covalent bond shortening and distortion induced by pressurization of thorium, uranium, and neptunium tetrakis aryloxides. Nature communications, 13 (1). p. 5923.

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Abstract

Covalency involving the 5f orbitals is regularly invoked to explain the reactivity, structure and spectroscopic properties of the actinides, but the ionic versus covalent nature of metal-ligand bonding in actinide complexes remains controversial. The tetrakis 2,6-di-tert-butylphenoxide complexes of Th, U and Np form an isostructural series of crystal structures containing approximately tetrahedral MO₄ cores. We show that up to 3 GPa the Th and U crystal structures show negative linear compressibility as the OMO angles distort. At 3 GPa the angles snap back to their original values, reverting to a tetrahedral geometry with an abrupt shortening of the M-O distances by up to 0.1 Å. The Np complex shows similar but smaller effects, transforming above 2.4 GPa. Electronic structure calculations associate the M-O bond shortening with a change in covalency resulting from increased contributions to the M-O bonding by the metal 6d and 5f orbitals, the combination promoting MO₄ flexibility at little cost in energy.

Item Type:	Article
Divisions:	Faculty of Science and Engineering > School of Physical Sciences
Depositing User:	Symplectic Admin
Date Deposited:	19 Mar 2024 08:36
Last Modified:	19 Mar 2024 08:37
DOI:	10.1038/s41467-022-33459-7
Related URLs:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3179666