TY - JOUR
T1 - Covalent bond shortening and distortion induced by pressurization of thorium, uranium, and neptunium tetrakis aryloxides
AU - Shephard, Jacob J.
AU - Berryman, Victoria E. J.
AU - Ochiai, Tatsumi
AU - Walter, Olaf
AU - Price, Amy N.
AU - Warren, Mark R.
AU - Arnold, Polly L.
AU - Kaltsoyannis, Nikolas
AU - Parsons, Simon
PY - 2022/10/7
Y1 - 2022/10/7
N2 - 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 in the metal 6d and 5f orbitals, the combination promoting MO4 flexibility at little cost in energy.
AB - 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 in the metal 6d and 5f orbitals, the combination promoting MO4 flexibility at little cost in energy.
U2 - 10.1038/s41467-022-33459-7
DO - 10.1038/s41467-022-33459-7
M3 - Article
SN - 2041-1723
VL - 13
JO - Nature Communications
JF - Nature Communications
M1 - 5923
ER -