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{(SiMe 2 NPh) 3 -tacn}] (tacn ¼ 1,4,7triazacyclononane), 1, with 0.0625 and 0.25 equiv. of elemental sulfur affords the sulfide-bridged U(IV) complex [{U((SiMe 2 NPh) 3 -tacn)} 2 (m-S)], 2, and the terminal persulfide U(V) complex [U{(SiMe 2 NPh) 3 -tacn}(h 2 -S 2 )], 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 S 8 by a U(III) complex. Complex 4 behaves as a S-atom transfer agent when reacted with PPh 3 , affording the persulfide-bridged diuranium(IV) complex [{U((SiMe 2 NPh) 3 -tacn)} 2 (m-h 2 :h 2 -S 2 )], 5, and S]PPh 3 .

Neodymium(III) Complexes Capable of Multi‐Electron Redox Chemistry

“…Elemental chalcogen activation has been previously noted with uranium, but generally persulfide (S 2 2− ) compounds result . Furthermore, the unusual twist‐boat metallacycle noted here for Nd is unique to the bottom of the Periodic Table; transition metal counterparts do not display this conformer.…”

Neodymium(III) Complexes Capable of Multi‐Electron Redox Chemistry

“…[20,21] Furthermore,t he unusual twist-boat metallacycle noted here for Nd is unique to the bottom of the Periodic Table;t ransition metal counterparts do not display this conformer. [20,21] Furthermore,t he unusual twist-boat metallacycle noted here for Nd is unique to the bottom of the Periodic Table;t ransition metal counterparts do not display this conformer.…”

Reactivity of uranium(iv) bridged chalcogenido complexes UIV–E–UIV(E = S, Se) with elemental sulfur and selenium: synthesis of polychalcogenido-bridged uranium complexes

“…(Table 2). These bond distances are at the shorter end of known S-S bond lengths observed in other uranium 1,19,50,[57][58][59][60][61] and transition metal complexes, [62][63][64][65][66] featuring the persuldo ligand S 2…”