skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Ion association with tetra- n-alkylammonium cations stabilizes higher-oxidation-state neptunium dioxocations

Abstract

Extended–coordination sphere interactions between dissolved metals and other ions, including electrolyte cations, are not known to perturb the electrochemical behavior of metal cations in water. Herein, we report the stabilization of higher–oxidation state Np dioxocations in aqueous chloride solutions by hydrophobic tetra-nalkylammonium (TAA +) cations—an effect not exerted by fully hydrated Li + cations under similar conditions. Experimental and molecular dynamics simulation results indicate that TAA + cations not only drive enhanced coordination of anionic Cl ligands to Np V/VI but also associate with the resulting Np complexes via non-covalent interactions, which together decrease the electrode potential of the Np VI/Np V couple by up to 220 mV (ΔΔG = –22.2 kJ mol –1). Understanding the solvation–dependent interplay between electrolyte cations and metal–oxo species opens an avenue for controlling the formation and redox properties of metal complexes in solution. As a result, it also provides valuable mechanistic insights into actinide separation processes that widely use quaternary ammonium cations as extractants or in room temperature ionic liquids.

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [3]
  1. Argonne National Lab. (ANL), Argonne, IL (United States); Clemson Univ., Anderson, SC (United States)
  2. Argonne National Lab. (ANL), Argonne, IL (United States); Northwestern Univ., Evanston, IL (United States)
  3. Argonne National Lab. (ANL), Argonne, IL (United States); 3M Corporate Research Analytical Lab., St. Paul, MN (United States)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division
OSTI Identifier:
1494551
Grant/Contract Number:  
AC02-06CH11357
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 10; Journal Issue: 1; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Estes, Shanna L., Qiao, Baofu, and Jin, Geng Bang. Ion association with tetra-n-alkylammonium cations stabilizes higher-oxidation-state neptunium dioxocations. United States: N. p., 2019. Web. doi:10.1038/s41467-018-07982-5.
Estes, Shanna L., Qiao, Baofu, & Jin, Geng Bang. Ion association with tetra-n-alkylammonium cations stabilizes higher-oxidation-state neptunium dioxocations. United States. doi:10.1038/s41467-018-07982-5.
Estes, Shanna L., Qiao, Baofu, and Jin, Geng Bang. Fri . "Ion association with tetra-n-alkylammonium cations stabilizes higher-oxidation-state neptunium dioxocations". United States. doi:10.1038/s41467-018-07982-5. https://www.osti.gov/servlets/purl/1494551.
@article{osti_1494551,
title = {Ion association with tetra-n-alkylammonium cations stabilizes higher-oxidation-state neptunium dioxocations},
author = {Estes, Shanna L. and Qiao, Baofu and Jin, Geng Bang},
abstractNote = {Extended–coordination sphere interactions between dissolved metals and other ions, including electrolyte cations, are not known to perturb the electrochemical behavior of metal cations in water. Herein, we report the stabilization of higher–oxidation state Np dioxocations in aqueous chloride solutions by hydrophobic tetra-nalkylammonium (TAA+) cations—an effect not exerted by fully hydrated Li+ cations under similar conditions. Experimental and molecular dynamics simulation results indicate that TAA+ cations not only drive enhanced coordination of anionic Cl– ligands to NpV/VI but also associate with the resulting Np complexes via non-covalent interactions, which together decrease the electrode potential of the NpVI/NpV couple by up to 220 mV (ΔΔG = –22.2 kJ mol–1). Understanding the solvation–dependent interplay between electrolyte cations and metal–oxo species opens an avenue for controlling the formation and redox properties of metal complexes in solution. As a result, it also provides valuable mechanistic insights into actinide separation processes that widely use quaternary ammonium cations as extractants or in room temperature ionic liquids.},
doi = {10.1038/s41467-018-07982-5},
journal = {Nature Communications},
issn = {2041-1723},
number = 1,
volume = 10,
place = {United States},
year = {2019},
month = {1}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Figures / Tables:

Fig. 1 Fig. 1: Effect of Li+ vs. [NMe4]+ on the NpVI/NpV couple. Currentnormalized cyclic voltammetry data for solutions of 5 mM NpV dissolved in 5M NMe4Cl or 5 M LiCl at pH ≈ 1.3. The arrow indicates the initial scan direction. Initial and cathodic switching potential= 400/550mV; anodic switching potential= 1000/1150mV;more » ν= 100mV s−1« less

Save / Share:

Works referenced in this record:

A short history of SHELX
journal, December 2007

  • Sheldrick, George M.
  • Acta Crystallographica Section A Foundations of Crystallography, Vol. 64, Issue 1, p. 112-122
  • DOI: 10.1107/S0108767307043930

    Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.