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Schacherl B, Joseph C, Lavrova P, Beck A, Reitz C, Prüssmann T, Fellhauer D, Lee JY, Dardenne K, Rothe J, Geckeis H, Vitova T. Paving the way for examination of coupled redox/solid-liquid interface reactions: 1 ppm Np adsorbed on clay studied by Np M5-edge HR-XANES spectroscopy. Anal Chim Acta 2022; 1202:339636. [DOI: 10.1016/j.aca.2022.339636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 02/06/2022] [Accepted: 02/17/2022] [Indexed: 11/01/2022]
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Réant BLL, Berryman VEJ, Basford AR, Nodaraki LE, Wooles AJ, Tuna F, Kaltsoyannis N, Mills DP, Liddle ST. 29Si NMR Spectroscopy as a Probe of s- and f-Block Metal(II)-Silanide Bond Covalency. J Am Chem Soc 2021; 143:9813-9824. [PMID: 34169713 DOI: 10.1021/jacs.1c03236] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report the use of 29Si NMR spectroscopy and DFT calculations combined to benchmark the covalency in the chemical bonding of s- and f-block metal-silicon bonds. The complexes [M(SitBu3)2(THF)2(THF)x] (1-M: M = Mg, Ca, Yb, x = 0; M = Sm, Eu, x = 1) and [M(SitBu2Me)2(THF)2(THF)x] (2-M: M = Mg, x = 0; M = Ca, Sm, Eu, Yb, x = 1) have been synthesized and characterized. DFT calculations and 29Si NMR spectroscopic analyses of 1-M and 2-M (M = Mg, Ca, Yb, No, the last in silico due to experimental unavailability) together with known {Si(SiMe3)3}--, {Si(SiMe2H)3}--, and {SiPh3}--substituted analogues provide 20 representative examples spanning five silanide ligands and four divalent metals, revealing that the metal-bound 29Si NMR isotropic chemical shifts, δSi, span a wide (∼225 ppm) range when the metal is kept constant, and direct, linear correlations are found between δSi and computed delocalization indices and quantum chemical topology interatomic exchange-correlation energies that are measures of bond covalency. The calculations reveal dominant s- and d-orbital character in the bonding of these silanide complexes, with no significant f-orbital contributions. The δSi is determined, relatively, by paramagnetic shielding for a given metal when the silanide is varied but by the spin-orbit shielding term when the metal is varied for a given ligand. The calculations suggest a covalency ordering of No(II) > Yb(II) > Ca(II) ≈ Mg(II), challenging the traditional view of late actinide chemical bonding being equivalent to that of the late lanthanides.
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Affiliation(s)
- Benjamin L L Réant
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Victoria E J Berryman
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Annabel R Basford
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Lydia E Nodaraki
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Ashley J Wooles
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Floriana Tuna
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Nikolas Kaltsoyannis
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - David P Mills
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Stephen T Liddle
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
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Curran DJ, Ganguly G, Heit YN, Wolford NJ, Minasian SG, Löble MW, Cary SK, Kozimor SA, Autschbach J, Neidig ML. Near-infrared C-term MCD spectroscopy of octahedral uranium(V) complexes. Dalton Trans 2021; 50:5483-5492. [PMID: 33908963 DOI: 10.1039/d1dt00513h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
C-term magnetic circular dichroism (MCD) spectroscopy is a powerful method for probing d-d and f-f transitions in paramagnetic metal complexes. However, this technique remains underdeveloped both experimentally and theoretically for studies of U(v) complexes of Oh symmetry, which have been of longstanding interest for probing electronic structure, bonding, and covalency in 5f systems. In this study, C-term NIR MCD of the Laporte forbidden f-f transitions of [UCl6]- and [UF6]- are reported, demonstrating the significant fine structure resolution possible with this technique including for the low energy Γ7 → Γ8 transitions in [UF6]-. The experimental NIR MCD studies were further extended to [U(OC6F5)6]-, [U(CH2SiMe3)6]-, and [U(NC(tBu)(Ph))6]- to evaluate the effects of ligand-type on the f-f MCD fine structure features. Theoretical calculations were conducted to determine the Laporte forbidden f-f transitions and their MCD intensity experimentally observed in the NIR spectra of the U(v) hexahalide complexes, via the inclusion of vibronic coupling, to better understand the underlying spectral fine structure features for these complexes. These spectra and simulations provide an important platform for the application of MCD spectroscopy to this widely studied class of U(v) complexes and identify areas for continued theoretical development.
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Affiliation(s)
- Daniel J Curran
- Department of Chemistry, University of Rochester, Rochester, New York 14627, USA.
| | - Gaurab Ganguly
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, USA.
| | - Yonaton N Heit
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, USA.
| | - Nikki J Wolford
- Department of Chemistry, University of Rochester, Rochester, New York 14627, USA.
| | - Stefan G Minasian
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Matthias W Löble
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | - Samantha K Cary
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | - Stosh A Kozimor
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | - Jochen Autschbach
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, USA.
| | - Michael L Neidig
- Department of Chemistry, University of Rochester, Rochester, New York 14627, USA.
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Actinide covalency measured by pulsed electron paramagnetic resonance spectroscopy. Nat Chem 2016; 9:578-583. [PMID: 28537586 DOI: 10.1038/nchem.2692] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 11/10/2016] [Indexed: 12/20/2022]
Abstract
Our knowledge of actinide chemical bonds lags far behind our understanding of the bonding regimes of any other series of elements. This is a major issue given the technological as well as fundamental importance of f-block elements. Some key chemical differences between actinides and lanthanides-and between different actinides-can be ascribed to minor differences in covalency, that is, the degree to which electrons are shared between the f-block element and coordinated ligands. Yet there are almost no direct measures of such covalency for actinides. Here we report the first pulsed electron paramagnetic resonance spectra of actinide compounds. We apply the hyperfine sublevel correlation technique to quantify the electron-spin density at ligand nuclei (via the weak hyperfine interactions) in molecular thorium(III) and uranium(III) species and therefore the extent of covalency. Such information will be important in developing our understanding of the chemical bonding, and therefore the reactivity, of actinides.
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Adam C, Beele BB, Geist A, Müllich U, Kaden P, Panak PJ. NMR and TRLFS studies of Ln(iii) and An(iii) C5-BPP complexes. Chem Sci 2015; 6:1548-1561. [PMID: 29560242 PMCID: PMC5811079 DOI: 10.1039/c4sc03103b] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 12/09/2014] [Indexed: 11/21/2022] Open
Abstract
C5-BPP is a highly efficient N-donor ligand for the separation of trivalent actinides, An(iii), from trivalent lanthanides, Ln(iii). The molecular origin of the selectivity of C5-BPP and many other N-donor ligands of the BTP-type is still not entirely understood. We present here the first NMR studies on C5-BPP Ln(iii) and An(iii) complexes. C5-BPP is synthesized with 10% 15N labeling and characterized by NMR and LIFDI-MS methods. 15N NMR spectroscopy gives a detailed insight into the bonding of C5-BPP with lanthanides and Am(iii) as a representative for trivalent actinide cations, revealing significant differences in 15N chemical shift for coordinating nitrogen atoms compared to Ln(iii) complexes. The temperature dependence of NMR chemical shifts observed for the Am(iii) complex indicates a weak paramagnetism. This as well as the observed large chemical shift for coordinating nitrogen atoms show that metal-ligand bonding in Am(C5-BPP)3 has a larger share of covalence than in lanthanide complexes, confirming earlier studies. The Am(C5-BPP)3 NMR sample is furthermore spiked with Cm(iii) and characterized by time-resolved laser fluorescence spectroscopy (TRLFS), yielding important information on the speciation of trace amounts of minor complex species.
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Affiliation(s)
- Christian Adam
- Karlsruhe Institute of Technology (KIT) , Institute for Nuclear Waste Disposal (INE) , P.O. Box 3640 , 76021 Karlsruhe , Germany .
- University of Heidelberg , Institute of Physical Chemistry , Im Neuenheimer Feld 253 , 69120 Heidelberg , Germany
| | - Björn B Beele
- Karlsruhe Institute of Technology (KIT) , Institute for Nuclear Waste Disposal (INE) , P.O. Box 3640 , 76021 Karlsruhe , Germany .
- University of Heidelberg , Institute of Physical Chemistry , Im Neuenheimer Feld 253 , 69120 Heidelberg , Germany
| | - Andreas Geist
- Karlsruhe Institute of Technology (KIT) , Institute for Nuclear Waste Disposal (INE) , P.O. Box 3640 , 76021 Karlsruhe , Germany .
| | - Udo Müllich
- Karlsruhe Institute of Technology (KIT) , Institute for Nuclear Waste Disposal (INE) , P.O. Box 3640 , 76021 Karlsruhe , Germany .
| | - Peter Kaden
- Karlsruhe Institute of Technology (KIT) , Institute for Nuclear Waste Disposal (INE) , P.O. Box 3640 , 76021 Karlsruhe , Germany .
| | - Petra J Panak
- Karlsruhe Institute of Technology (KIT) , Institute for Nuclear Waste Disposal (INE) , P.O. Box 3640 , 76021 Karlsruhe , Germany .
- University of Heidelberg , Institute of Physical Chemistry , Im Neuenheimer Feld 253 , 69120 Heidelberg , Germany
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