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Fetrow T, Cashman BK, Carpenter SH, Janicke MT, Anderson NH, Klamm BE, Mason HE, Tondreau AM. Oxidative Dissolution of Lanthanide Metals Ce and Ho in Molten GaCl 3. Inorg Chem 2024; 63:9385-9389. [PMID: 37851526 PMCID: PMC11135323 DOI: 10.1021/acs.inorgchem.3c02774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Indexed: 10/20/2023]
Abstract
Gallium trichloride (GaCl3) was used as a solvent for the oxidative dissolution of the lanthanide (Ln) metals cerium (Ce) and holmium (Ho). Reactions were performed at temperatures above 100 °C in sealed vessels to maintain the liquid phase for GaCl3 during the oxidizing reactions. The best results were obtained from reactions using 8 equiv of GaCl3 to metal where the inorganic complexes [Ga][Ln(GaCl4)4] [Ln = Ce (1), Ho (2)] could be isolated. Recrystallization of 1 and 2 employing fluorobenzene (C6H5F) produced [Ga(η6-C6H5F)2][Ln(GaCl4)4] [Ln = Ce (3), Ho (4)] where reversible η6 coordination of C6H5F to [Ga]+ was observed. All complexes were characterized through elemental analysis (F and Cl), IR and UV-vis-near-IR spectroscopies, and both solution and solid-state NMR techniques.
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Affiliation(s)
- Taylor
V. Fetrow
- Pit
Technologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Brenna K. Cashman
- Chemistry
Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Stephanie H. Carpenter
- Chemistry
Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Michael T. Janicke
- Chemistry
Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Nickolas H. Anderson
- Pit
Technologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Bonnie E. Klamm
- Pit
Technologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Harris E. Mason
- Chemistry
Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Aaron M. Tondreau
- Chemistry
Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
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Kravchuk DV, Augustine LJ, Rajapaksha H, Benthin GC, Batista ER, Yang P, Forbes TZ. Insights into the Mechanism of Neptunium Oxidation to the Heptavalent State. Chemistry 2024; 30:e202304049. [PMID: 38183632 DOI: 10.1002/chem.202304049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 12/29/2023] [Accepted: 01/02/2024] [Indexed: 01/08/2024]
Abstract
Neptunium can exist in multiple oxidation states, including the rare and poorly understood heptavalent form. In this work, we monitored the formation of heptavalent neptunium [Np(VII)O4(OH)2]3- during ozonolysis of aqueous MOH (M=Li, Na, K) solutions using a combined experimental and theoretical approach. All experimental reactions were closely monitored via absorption and vibrational spectroscopy to follow both the oxidation state and the speciation of neptunium guided by the calculated vibrational frequencies for various neptunium species. The mechanism of the reaction partly involves oxidative dissolution of transient Np(VI) oxide/hydroxide solid phases, the identity of which are dependent on the co-precipitating counter-cation Li+/Na+/K+. Additional calculations suggest that the most favorable energetic pathway occurs through the reaction of a [Np(V)O2(OH)4]3- with the hydroxide radical to form [Np(VI)O2(OH)4]2-, followed by an additional oxidation with HO⋅ to create [Np(VII)O4(OH)2]3-.
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Affiliation(s)
- Dmytro V Kravchuk
- Department of Chemistry, University of Iowa, Iowa City, Iowa, 52242, United States
| | - Logan J Augustine
- Department of Chemistry, University of Iowa, Iowa City, Iowa, 52242, United States
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, United States
| | - Harindu Rajapaksha
- Department of Chemistry, University of Iowa, Iowa City, Iowa, 52242, United States
| | - Grant C Benthin
- Department of Chemistry, University of Iowa, Iowa City, Iowa, 52242, United States
| | - Enrique R Batista
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, United States
| | - Ping Yang
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, United States
| | - Tori Z Forbes
- Department of Chemistry, University of Iowa, Iowa City, Iowa, 52242, United States
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Boggiano AC, Studvick CM, Steiner A, Bacsa J, Popov IA, La Pierre HS. Structural distortion by alkali metal cations modulates the redox and electronic properties of Ce 3+ imidophosphorane complexes. Chem Sci 2023; 14:11708-11717. [PMID: 37920331 PMCID: PMC10619540 DOI: 10.1039/d3sc04262f] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 09/15/2023] [Indexed: 11/04/2023] Open
Abstract
A series of Ce3+ complexes with counter cations ranging from Li to Cs are presented. Cyclic voltammetry data indicate a significant dependence of the oxidation potential on the alkali metal identity. Analysis of the single-crystal X-ray diffraction data indicates that the degree of structural distortion of the secondary coordination sphere is linearly correlated with the measured oxidation potential. Solution electronic absorption spectroscopy confirms that the structural distortion is reflected in the solution structure. Computational studies further validate this analysis, deciphering the impact of alkali metal cations on the Ce atomic orbital contributions, differences in energies of Ce-dominant molecular orbitals, energy shift of the 4f-5d electronic transitions, and degree of structural distortions. In sum, the structural impact of the alkali metal cation is demonstrated to modulate the redox and electronic properties of the Ce3+ complexes, and provides insight into the rational tuning of the Ce3+ imidophosphorane complex oxidation potential through alkali metal identity.
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Affiliation(s)
- Andrew C Boggiano
- School of Chemistry and Biochemistry, Georgia Institute of Technology Atlanta Georgia 30332-0400 USA
| | - Chad M Studvick
- Department of Chemistry, The University of Akron Akron Ohio 44325-3601 USA
| | - Alexander Steiner
- Department of Chemistry, University of Liverpool Liverpool L69 7ZD UK
| | - John Bacsa
- School of Chemistry and Biochemistry, Georgia Institute of Technology Atlanta Georgia 30332-0400 USA
| | - Ivan A Popov
- Department of Chemistry, The University of Akron Akron Ohio 44325-3601 USA
| | - Henry S La Pierre
- School of Chemistry and Biochemistry, Georgia Institute of Technology Atlanta Georgia 30332-0400 USA
- Nuclear and Radiological Engineering and Medical Physics Program, School of Mechanical Engineering, Georgia Institute of Technology Atlanta Georgia 30332-0400 USA
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Li B, Jones ZR, Eiroa-Lledo C, Knope KE, Mocko V, Stein BW, Wacker JN, Kozimor SA, Batista ER, Yang P. Structure and Dynamics of NaCl/KCl/CaCl 2-EuCl n ( n = 2, 3) Molten Salts. Inorg Chem 2023. [PMID: 37379331 DOI: 10.1021/acs.inorgchem.2c03982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/30/2023]
Abstract
Modern molten salt reactor design and the techniques of electrorefining spent nuclear fuels require a better understanding of the chemical and physical behavior of lanthanide/actinide ions with different oxidation states dissolved in various solvent salts. The molecular structures and dynamics that are driven by the short-range interactions between solute cations and anions and long-range solute and solvent cations are still unclear. In order to study the structural change of solute cations caused by different solvent salts, we performed first-principles molecular dynamics simulations in molten salts and extended X-ray absorption fine structure (EXAFS) measurements for the cooled molten salt samples to identify the local coordination environment of Eu2+ and Eu3+ ions in CaCl2, NaCl, and KCl. The simulations reveal that with the increasing polarizing the outer sphere cations from K+ to Na+ to Ca2+, the coordination number (CN) of Cl- in the first solvation shell increases from 5.6 (Eu2+) and 5.9 (Eu3+) in KCl to 6.9 (Eu2+) and 7.0 (Eu3+) in CaCl2. This coordination change is validated by the EXAFS measurements, in which the CN of Cl- around Eu increases from 5 in KCl to 7 in CaCl2. Our simulation shows that the fewer Cl- ions coordinated to Eu leads to a more rigid first coordination shell with longer lifetime. Furthermore, the diffusivities of Eu2+/Eu3+ are related to the rigidity of their first coordination shell of Cl-: the more rigid the first coordination shell is, the slower the solute cations diffuse.
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Affiliation(s)
- Bo Li
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Zachary R Jones
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Cecilia Eiroa-Lledo
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Karah E Knope
- Department of Chemistry, Georgetown University, 37th and O Streets NW, Washington, D.C. 20057, United States
| | - Veronika Mocko
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Benjamin W Stein
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Jennifer N Wacker
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
- Department of Chemistry, Georgetown University, 37th and O Streets NW, Washington, D.C. 20057, United States
| | - Stosh A Kozimor
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Enrique R Batista
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Ping Yang
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
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Unger AJ, Jensen MP. Room-Temperature Ionic Liquid Cation Effects on the Structure and Stability of Anionic Lanthanide Complexes. Inorg Chem 2023; 62:5553-5564. [PMID: 36976891 DOI: 10.1021/acs.inorgchem.3c00050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
Room-temperature ionic liquids (RTILs) are a subset of molten salts that are liquids at room temperature and may offer an elegant, low-temperature route to predicting the properties of solvated metal complexes in their high-temperature analogues. This work studied the chemistry of chloride anion-containing RTILs to determine their similarity to inorganic molten chloride salts. The behaviors of complexes of Mn, Nd, and Eu were evaluated in a variety of chloride RTILs by absorption spectrophotometry and electrochemistry to elucidate trends in cation effects on the coordination geometry and redox properties of the solvated species. Spectrophotometric data indicated the metals are present as anionic complex (e.g., MnCl42- and NdCl63-) analogous to those observed in molten chloride salts. Strongly polarizing, charge-dense RTIL cations induced distortions to the symmetry of these complexes, resulting in lower oscillator strengths and red-shifted energies for the observed transitions. Cyclic voltammetry experiments were used to characterize the Eu(III/II) redox couple producing diffusion coefficients on the order of 10-8 cm2 s-1 and heterogeneous electron transfer rate constants ranging between 6 × 10-5 and 2 × 10-4 cm s-1. The E1/2 potentials for Eu(III/II) were also found to shift positively with increasing cation polarization power, stabilizing the Eu(II) oxidation state by removing electron density from the metal center over chloride bond networks. Both the optical spectrophotometry and electrochemistry results suggest that the polarization strength of an RTIL cation plays a major role in the geometry and stability of a metal complex.
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