Issue 2, 2014

Two-electron versus one-electron reduction of chalcogens by uranium(iii): synthesis of a terminal U(v) persulfide complex

Abstract

The reaction of the tripodal tris-amido U(III) complex [U{(SiMe2NPh)3–tacn}] (tacn = 1,4,7-triazacyclononane), 1, with 0.0625 and 0.25 equiv. of elemental sulfur affords the sulfide-bridged U(IV) complex [{U((SiMe2NPh)3–tacn)}2(μ-S)], 2, and the terminal persulfide U(V) complex [U{(SiMe2NPh)3–tacn}(η2-S2)], 4, respectively, in good yield. Two different electronic structures, U(V) persulfide and U(IV) supersulfide, were computed for complex 4 at the DFT level. The results show that complex 4 is best described as a U(V) persulfide species with a significant sulfur contribution. X-ray, magnetism and electrochemistry data support this description. Complex 4 is the first example of a terminal U(V) persulfide and of a two-electron reduction of S8 by a U(III) complex. Complex 4 behaves as a S-atom transfer agent when reacted with PPh3, affording the persulfide-bridged diuranium(IV) complex [{U((SiMe2NPh)3–tacn)}2(μ-η22-S2)], 5, and S[double bond, length as m-dash]PPh3.

Graphical abstract: Two-electron versus one-electron reduction of chalcogens by uranium(iii): synthesis of a terminal U(v) persulfide complex

Supplementary files

Article information

Article type
Edge Article
Submitted
01 Oct 2013
Accepted
29 Oct 2013
First published
29 Oct 2013

Chem. Sci., 2014,5, 841-846

Two-electron versus one-electron reduction of chalcogens by uranium(III): synthesis of a terminal U(V) persulfide complex

C. Camp, M. A. Antunes, G. García, I. Ciofini, I. C. Santos, J. Pécaut, M. Almeida, J. Marçalo and M. Mazzanti, Chem. Sci., 2014, 5, 841 DOI: 10.1039/C3SC52742E

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