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DOE OSTI · 3366116

Quantifying Outer- and Inner-Coordination Sphere Effects Using Uranium Redox Chemistry in Molten Salt Solutions

Marshall-Roth, Travis [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000262456404)·MacInnes, Molly M. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000195137402)·Jordan, Aldo M. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)]·Piedmonte, Ida D. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)]·Pace, Kristen A. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000185748939)·Adelman, Sara L. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000179893451)·Anderson, Nickolas H. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000151025070)·Cooley, Jason C. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000226492352)·Kozimor, Stosh A. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000173870507)·Mullis, Monica S. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0009000719655890)·Mocko, Veronika [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000160416778)·Rocha, Francisca R. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000303080184)·Stein, Benjamin W. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000203665476)
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Abstract

Defining the relative influence of intramolecular and intermolecular forces is a fundamental problem in chemistry that is difficult to quantify. To address this challenge, we developed a method to evaluate the relative impact of direct chemical bonding in the inner-coordination sphere vs effects from cations in the outer-coordination sphere by comparative analysis of uranium redox reactivity in various molten salts. We observed that outer-coordination sphere cations (M 1+ ) and inner-coordination sphere anions (X 1– ) both affected uranium redox reactivity, with more polarizing M 1+ and larger X 1– favoring uranium in low oxidation states. Changing M 1+ (Li, Na, K) shifted the U IV + e 1– ⇌ U III (U IV/III ) and U III + 3e 1– → U 0 metal potentials by +330 and +240 mV, respectively. Changing X 1– (Cl, Br, I) caused larger shifts of +440 mV for the U IV/III redox potential and +1060 mV for the U 0 metal deposition potential. Using Coulomb’s Law, we correlated these potentials with electrostatic interactions between UIII and the molten salt. This model provided a facile way of predicting redox chemistry within molten salts.

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Marshall-Roth, Travis [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000262456404), MacInnes, Molly M. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000195137402), Jordan, Aldo M. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)], Piedmonte, Ida D. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)], Pace, Kristen A. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000185748939), Adelman, Sara L. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000179893451), Anderson, Nickolas H. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000151025070), Cooley, Jason C. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000226492352), Kozimor, Stosh A. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000173870507), Mullis, Monica S. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0009000719655890), Mocko, Veronika [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000160416778), Rocha, Francisca R. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000303080184), Stein, Benjamin W. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000203665476). 2026-04-14. Quantifying Outer- and Inner-Coordination Sphere Effects Using Uranium Redox Chemistry in Molten Salt Solutions. https://doi.org/10.1021/jacs.5c20789

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