Journal article
Holistic Assessment of Actinide-Borohydride Covalency Using NMR and X-ray Absorption Spectroscopies
Journal of the American Chemical Society
09/22/2026
DOI: 10.1021/jacs.6c02674
Appears in UI Libraries Support Open Access
Abstract
The influence of metal-ligand covalency on actinide electronic properties and reactivity continues to be a topic of intense interest given its implications for nuclear and radiochemical applications. Extensive work has focused on developing spectroscopic methods that can be used to quantify metal-ligand covalency within actinide complexes for benchmarking and comparison with theoretical efforts. Ligand K-edge X-ray absorption spectroscopy (XAS) and NMR spectroscopy are two physical methods that have dominated these efforts, but surprisingly, they have not been used together on the same systems to see how the methods compare. Herein, we report the first comparative assessment of actinide-ligand covalency using B K-edge XAS and multinuclear NMR spectroscopy. The B K-edge XAS spectra of An(κ3-BH4)(NR2)3 (R = SiMe3) with An = Th (1) and U (2) reveal a dominant feature assigned to B 1s → An–H–B π* MOs due to covalent three-center, two-electron bonding with the actinide 6d orbitals, as revealed by comparison with time-dependent density functional theory (TDDFT) calculations. By contrast, the data indicate that 5f-orbital contributions to the bonds are significantly smaller. These findings were corroborated by 1H and 11B NMR studies of diamagnetic 1 and DFT calculations used to quantify the impact of orbital mixing via spin-orbit coupling on the chemical shifts. These results represent the first instance of using B K-edge XAS and 11B NMR spectroscopy to assess covalency in actinide complexes. Moreover, they demonstrate how ligand K-edge XAS, which provides rich orbital-specific information relevant to chemical bonding, and NMR spectroscopy, which is routinely available in most chemical research settings, can be used as complementary techniques to provide a holistic assessment of covalency in actinide-ligand bonds.
Details
- Title: Subtitle
- Holistic Assessment of Actinide-Borohydride Covalency Using NMR and X-ray Absorption Spectroscopies
- Creators
- Hannah M. Hansen - University of IowaNathan R. Loutsch - University of IowaThien H. Nguyen - University of California, Santa BarbaraAaron Christianson - University of IowaJacob J. Schuely - University of IowaMai Yer Yang - University of IowaPeter A. Zacher - University of IowaLucia Zuin - University of SaskatchewanTrevor W. Hayton - University of California, Santa BarbaraBess Vlaisavljevich - University of IowaScott R. Daly - University of Iowa
- Resource Type
- Journal article
- Publication Details
- Journal of the American Chemical Society
- DOI
- 10.1021/jacs.6c02674
- ISSN
- 0002-7863
- eISSN
- 1520-5126
- Publisher
- American Chemical Society
- Grant note
- National Nuclear Security Administration: DE-NA0004151 National Science Foundation (NSF): CHE-2247235
We thank the National Nuclear Security Administration (NNSA) for the generous support of this work under award number DE-NA0004151. MYY thanks the NSF for supporting her travel to the CLS (award CHE-2247235). B K-edge XAS measurements were performed at beamline VLS-PGM at the Canadian Light Source, a national research facility of the University of Saskatchewan, which is supported by the Canada Foundation for Innovation (CFI), the Natural Sciences and Engineering Research Council (NSERC), the National Research Council (NRC), the Canadian Institutes of Health Research (CIHR), the Government of Saskatchewan, and the University of Saskatchewan. This research was further supported through computational resources provided by the University of Iowa.
- Language
- English
- Electronic publication date
- 09/22/2026
- Academic Unit
- Chemistry
- Record Identifier
- 9985236420102771
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