Issue 24, 2018

Complexation-assisted reduction: complexes of glutaroimide-dioxime with tetravalent actinides (Np(iv) and Th(iv))

Abstract

Glutaroimide-dioxime forms strong complexes with tetravalent Th(IV) and Np(IV) in aqueous solution. In conjunction with literature data on the complexation of glutaroimide-dioxime with other metal ions, it was found that the complexes become weaker as the effective charge density on the metal ions decreases: V5+ > Th4+ ≈ Fe3+ > UO22+ > Eu3+/Nd3+ > Cu2+ > Pb2+ > NpO2+ > Ca2+/Mg2+. In the glutaroimide-dioxime complexes with Th(IV) and Np(IV), deprotonation of the imide group and relocation of the two hydrogen atoms from oxygen to nitrogen of the oxime groups result in a large conjugated system (–O–N–C–N–C–N–O–) that coordinates strongly to the metal center in a tridentate mode via the central imide nitrogen atom and the two oxime oxygen atoms. Because the stability of glutaroimide-dioxime complexes with Np(IV) is much higher than those with Np(V), the redox potential of the Np(V)/Np(IV) couple is expected to be shifted significantly. As a result, crystals of glutaroimide-dioxime complexes with Np(IV) were readily obtained from initial solutions containing Np(V). A mechanism of complexation-assisted reduction integrating the thermodynamic and structural data from this work is discussed.

Graphical abstract: Complexation-assisted reduction: complexes of glutaroimide-dioxime with tetravalent actinides (Np(iv) and Th(iv))

Supplementary files

Article information

Article type
Paper
Submitted
27 Mar 2018
Accepted
21 May 2018
First published
22 May 2018

Dalton Trans., 2018,47, 8134-8141

Author version available

Complexation-assisted reduction: complexes of glutaroimide-dioxime with tetravalent actinides (Np(IV) and Th(IV))

Z. Zhang, B. F. Parker, T. D. Lohrey, S. J. Teat, J. Arnold and L. Rao, Dalton Trans., 2018, 47, 8134 DOI: 10.1039/C8DT01191E

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