Journal article
Inverse Trans Influence and Uranium-Arene σ-Bonding Drive Molecular Geometry: Ligand Modification from Hard to Soft Flips the Oxide from Axial to Equatorial
Journal of the American Chemical Society, Vol.147(31), pp.27515-27524
08/06/2025
DOI: 10.1021/jacs.5c05029
PMID: 40699154
Abstract
A rare example of an equatorially bound terminal uranium(V) oxo complex in a chelating sulfur-based ligand environment, namely [(mes(Me,AdArS)3)UV(Oeq)(THF)] (2), is presented. Octahedrally coordinated 2 is obtained by reaction of the mesitylene-anchored tris-thiophenolate-coordinated uranium(III) complex [UIII((SArAd,Me)3mes)] (1) with the oxygen-atom transfer reagent N2O. The observed, equatorially bound oxo ligand in 2 is in stark contrast to its known tris-aryloxide analog, [(mes(Me,AdArO)3)UV(Oax)(THF)] (A), where the oxo ligand occupies the typically observed axial coordination site. Complexes 1 and 2 are characterized by single-crystal X-ray diffraction analyses and spectroscopic and magnetochemical methods, including 1H NMR, UV/vis/NIR electronic absorption, as well as EPR spectroscopy and SQUID magnetometry, thus confirming the CS symmetry and the pentavalent oxidation state of 2. Encompassing quantum chemical calculations (DFT and CASPT2) on 2 and its tris-phenolate analog A, support and rationalize the structural and electronic differences. The molecular orbital pictures show that a stabilizing σ-bonding interaction arising from the U–Oeq inverse trans influence (ITI) is present in 2 but missing in A. In 2, the sulfur 3p orbitals are closer in energy to the uranium 5f manifold than the arene π-system, leading to an ITI, while U–arene σ- or δ-bonding is not observed. Although the arene orbitals remain separated from the uranium 5f orbitals in A, the absence of an ITI allows the arene a2u orbital to engage in a σ-type interaction with the metal. Thus, incorporating a tris-thiophenolate to an arene anchor introduces a new design concept in molecular f-element chemistry. This approach stabilizes an equatorially bound U(V) oxo center, contrasting with its tris-phenolate counterpart, where oxo coordination is axial. The observed geometric divergence, driven by competing ITI and U–arene interactions, not only tunes electronic structure but also leads to differentiated reactivity: only the phenolate analogs activate H2O, while the thiolates do not.
Details
- Title: Subtitle
- Inverse Trans Influence and Uranium-Arene σ-Bonding Drive Molecular Geometry: Ligand Modification from Hard to Soft Flips the Oxide from Axial to Equatorial
- Creators
- Benedikt Kestel - Friedrich-Alexander-Universität Erlangen-NürnbergDaniel Pividori - Friedrich-Alexander-Universität Erlangen-NürnbergSabyasachi Roy Chowdhury - University of South DakotaFrank W Heinemann - Friedrich-Alexander-Universität Erlangen-NürnbergBess Vlaisavljevich - University of South DakotaKarsten Meyer - Friedrich-Alexander-Universität Erlangen-Nürnberg
- Resource Type
- Journal article
- Publication Details
- Journal of the American Chemical Society, Vol.147(31), pp.27515-27524
- DOI
- 10.1021/jacs.5c05029
- PMID
- 40699154
- NLM abbreviation
- J Am Chem Soc
- ISSN
- 1520-5126
- eISSN
- 1520-5126
- Publisher
- American Chemical Society
- Grant note
- Basic Energy SciencesFriedrich-Alexander-Universitat Erlangen-Nurnberg (FAU)Bundesministerium fur Bildung und Forschung (f-Char): 02NUK059E BMBF: DE-SC0025311 U.S. Department of Energy, Office of Science, Basic Energy Sciences, in the Heavy Element Chemistry program: OAC-1626516 NSF
Dedicated to Franc Meyer (Gottingen) and Christian Limberg (Berlin) in celebration of their combined 120 years of life, friendship, and outstanding contributions to inorganic chemistry. Friedrich-Alexander-Universitat Erlangen-Nurnberg (FAU) and the Bundesministerium fur Bildung und Forschung (f-Char, BMBF support code 02NUK059E) are gratefully acknowledged for generous funding. We thank Dominik Fehn and Eva Korber (FAU) for the EPR measurements. B.V. and S.R.C. were supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, in the Heavy Element Chemistry program (Grant No. DE-SC0025311). Computations supporting this project performed on high-performance computing systems were made possible by resources funded by NSF award OAC-1626516. The authors thank Jim Boncella for his inspiring presentations on actinide-arene chemistry and for his valuable discussions.
- Language
- English
- Electronic publication date
- 07/23/2025
- Date published
- 08/06/2025
- Academic Unit
- Chemistry
- Record Identifier
- 9984865310402771
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