Spontaneous Chelation‐Driven Reduction of the Neptunyl Cation in Aqueous Solution

Korey P Carter; Kurt F Smith; Toni Tratnjek; Katherine M Shield; Liane M Moreau; Julian A Rees; Corwin H Booth; Rebecca J Abergel

doi:10.1002/chem.201905695

Journal article

Spontaneous Chelation‐Driven Reduction of the Neptunyl Cation in Aqueous Solution

Korey P Carter, Kurt F Smith, Toni Tratnjek, Katherine M Shield, Liane M Moreau, Julian A Rees, Corwin H Booth and Rebecca J Abergel

Chemistry : a European journal, Vol.26(11), pp.2354-2359

02/21/2020

DOI: 10.1002/chem.201905695

PMID: 31914232

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Abstract

Octadentate hydroxypyridinone (HOPO) and catecholamide (CAM) siderophore analogues are known to be efficacious chelators of the actinide cations, and these ligands are also capable of facilitating both activation and reduction of actinyl species. Utilizing X‐ray absorption near edge structure (XANES) and extended X‐ray absorption fine structure (EXAFS) spectroscopies, as well as cyclic voltammetry measurements, herein, we elucidate chelation‐based mechanisms for driving reactivity and initiating redox processes in a family of neptunyl–HOPO and CAM complexes. Based on the selected chelator, the ability to control the oxidation state of neptunium and the speed of reduction and concurrent oxo group activation was demonstrated. Most notably, reduction kinetics for the NpVO2+//NpIV redox couple upon chelation by the ligands 3,4,3‐LI(1,2‐HOPO) and 3,4,3‐LI(CAM)2(1,2‐HOPO)2 was observed to be faster than ever reported, and in fact quicker than we could measure using either X‐ray absorption spectroscopy or electrochemical techniques. Spontaneous chelation‐driven reduction of the NpO2+ moiety was observed in the condensed phase. X‐ray absorption near edge structure (XANES) and extended X‐ray absorption fine structure (EXAFS) spectroscopy on Np‐343 ligand complexes confirmed metal‐ion reduction, providing some of the first structural data on a mixed valent NpV/NpIV chelate (see scheme).

Electrochemistry

actinides

chelation

neptunium

X-ray absorption

Details

Title: Subtitle: Spontaneous Chelation‐Driven Reduction of the Neptunyl Cation in Aqueous Solution
Creators: Korey P Carter - Lawrence Berkeley National Laboratory
Kurt F Smith - Lawrence Berkeley National Laboratory
Toni Tratnjek - Lawrence Berkeley National Laboratory
Katherine M Shield - University of California
Liane M Moreau - Lawrence Berkeley National Laboratory
Julian A Rees - Lawrence Berkeley National Laboratory
Corwin H Booth - Lawrence Berkeley National Laboratory
Rebecca J Abergel - University of California
Resource Type: Journal article
Publication Details: Chemistry : a European journal, Vol.26(11), pp.2354-2359
DOI: 10.1002/chem.201905695
PMID: 31914232
NLM abbreviation: Chemistry
ISSN: 0947-6539
eISSN: 1521-3765
Number of pages: 6
Grant note: Basic Energy Sciences (DE-AC02-05CH1123)
Language: English
Date published: 02/21/2020
Academic Unit: Chemistry
Record Identifier: 9984216700302771

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