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Title: Advancing Understanding of the +4 Metal Extractant Thenoyltrifluoroacetonate (TTA ); Synthesis and Structure of M IVTTA 4 (M IV = Zr, Hf, Ce, Th, U, Np, Pu) and M III(TTA) 4 (M III = Ce, Nd, Sm, Yb)

Abstract

Thenoyltrifluoroacetone (HTTA)-based extractions represent popular methods for separating microscopic amounts of transuranic actinides (i.e., Np and Pu) from macroscopic actinide matrixes (e.g. bulk uranium). It is well-established that this procedure enables +4 actinides to be selectively removed from +3, + 5, and +6 f-elements. However, even highly skilled and well-trained researchers find this process complicated and (at times) unpredictable. It is difficult to improve the HTTA extraction—or find alternatives—because little is understood about why this separation works. Even the identities of the extracted species are unknown. In addressing this knowledge gap, we report in this paper advances in fundamental understanding of the HTTA-based extraction. This effort included comparatively evaluating HTTA complexation with +4 and +3 metals (M IV = Zr, Hf, Ce, Th, U, Np, and Pu vs M III = Ce, Nd, Sm, and Yb). We observed +4 metals formed neutral complexes of the general formula M IV(TTA) 4. Meanwhile, +3 metals formed anionic M III(TTA) 4 species. Characterization of these M(TTA) 4 x– (x = 0, 1) compounds by UV–vis–NIR, IR, 1H and 19F NMR, single-crystal X-ray diffraction, and X-ray absorption spectroscopy (both near-edge and extended fine structure) was critical for determining that Np IV(TTA) 4 andmore » Pu IV(TTA) 4 were the primary species extracted by HTTA. Furthermore, this information lays the foundation to begin developing and understanding of why the HTTA extraction works so well. The data suggest that the solubility differences between M IV(TTA) 4 and M III(TTA) 4 are likely a major contributor to the selectivity of HTTA extractions for +4 cations over +3 metals. Finally and moreover, these results will enable future studies focused on explaining HTTA extractions preference for +4 cations, which increases from Np IV to Pu IV, Hf IV, and Zr IV.« less

Authors:
ORCiD logo [1];  [2];  [1]; ORCiD logo [1];  [1];  [1];  [1];  [1]; ORCiD logo [2]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Univ. of New Mexico, Albuquerque, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); USDOE National Nuclear Security Administration (NNSA); LANL Laboratory Directed Research and Development (LDRD) Program; National Science Foundation (NSF); National Inst. of Health (NIH) (United States)
OSTI Identifier:
1435518
Report Number(s):
LA-UR-17-25117
Journal ID: ISSN 0020-1669
Grant/Contract Number:
AC52-06NA25396; AC02-76SF00515; CHE 1602240; P41GM103393
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Inorganic Chemistry
Additional Journal Information:
Journal Volume: 57; Journal Issue: 7; Journal ID: ISSN 0020-1669
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Cary, Samantha K., Livshits, Maksim, Cross, Justin N., Ferrier, Maryline G., Mocko, Veronika, Stein, Benjamin W., Kozimor, Stosh A., Scott, Brian L., and Rack, Jeffrey J. Advancing Understanding of the +4 Metal Extractant Thenoyltrifluoroacetonate (TTA–); Synthesis and Structure of MIVTTA4 (MIV = Zr, Hf, Ce, Th, U, Np, Pu) and MIII(TTA)4– (MIII = Ce, Nd, Sm, Yb). United States: N. p., 2018. Web. doi:10.1021/acs.inorgchem.7b03089.
Cary, Samantha K., Livshits, Maksim, Cross, Justin N., Ferrier, Maryline G., Mocko, Veronika, Stein, Benjamin W., Kozimor, Stosh A., Scott, Brian L., & Rack, Jeffrey J. Advancing Understanding of the +4 Metal Extractant Thenoyltrifluoroacetonate (TTA–); Synthesis and Structure of MIVTTA4 (MIV = Zr, Hf, Ce, Th, U, Np, Pu) and MIII(TTA)4– (MIII = Ce, Nd, Sm, Yb). United States. doi:10.1021/acs.inorgchem.7b03089.
Cary, Samantha K., Livshits, Maksim, Cross, Justin N., Ferrier, Maryline G., Mocko, Veronika, Stein, Benjamin W., Kozimor, Stosh A., Scott, Brian L., and Rack, Jeffrey J. Wed . "Advancing Understanding of the +4 Metal Extractant Thenoyltrifluoroacetonate (TTA–); Synthesis and Structure of MIVTTA4 (MIV = Zr, Hf, Ce, Th, U, Np, Pu) and MIII(TTA)4– (MIII = Ce, Nd, Sm, Yb)". United States. doi:10.1021/acs.inorgchem.7b03089.
@article{osti_1435518,
title = {Advancing Understanding of the +4 Metal Extractant Thenoyltrifluoroacetonate (TTA–); Synthesis and Structure of MIVTTA4 (MIV = Zr, Hf, Ce, Th, U, Np, Pu) and MIII(TTA)4– (MIII = Ce, Nd, Sm, Yb)},
author = {Cary, Samantha K. and Livshits, Maksim and Cross, Justin N. and Ferrier, Maryline G. and Mocko, Veronika and Stein, Benjamin W. and Kozimor, Stosh A. and Scott, Brian L. and Rack, Jeffrey J.},
abstractNote = {Thenoyltrifluoroacetone (HTTA)-based extractions represent popular methods for separating microscopic amounts of transuranic actinides (i.e., Np and Pu) from macroscopic actinide matrixes (e.g. bulk uranium). It is well-established that this procedure enables +4 actinides to be selectively removed from +3, + 5, and +6 f-elements. However, even highly skilled and well-trained researchers find this process complicated and (at times) unpredictable. It is difficult to improve the HTTA extraction—or find alternatives—because little is understood about why this separation works. Even the identities of the extracted species are unknown. In addressing this knowledge gap, we report in this paper advances in fundamental understanding of the HTTA-based extraction. This effort included comparatively evaluating HTTA complexation with +4 and +3 metals (MIV = Zr, Hf, Ce, Th, U, Np, and Pu vs MIII = Ce, Nd, Sm, and Yb). We observed +4 metals formed neutral complexes of the general formula MIV(TTA)4. Meanwhile, +3 metals formed anionic MIII(TTA)4– species. Characterization of these M(TTA)4x– (x = 0, 1) compounds by UV–vis–NIR, IR, 1H and 19F NMR, single-crystal X-ray diffraction, and X-ray absorption spectroscopy (both near-edge and extended fine structure) was critical for determining that NpIV(TTA)4 and PuIV(TTA)4 were the primary species extracted by HTTA. Furthermore, this information lays the foundation to begin developing and understanding of why the HTTA extraction works so well. The data suggest that the solubility differences between MIV(TTA)4 and MIII(TTA)4– are likely a major contributor to the selectivity of HTTA extractions for +4 cations over +3 metals. Finally and moreover, these results will enable future studies focused on explaining HTTA extractions preference for +4 cations, which increases from Np IV to PuIV, HfIV, and ZrIV.},
doi = {10.1021/acs.inorgchem.7b03089},
journal = {Inorganic Chemistry},
number = 7,
volume = 57,
place = {United States},
year = {Wed Mar 21 00:00:00 EDT 2018},
month = {Wed Mar 21 00:00:00 EDT 2018}
}

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