Synthesis, structure and redox properties of single-atom bridged diuranium complexes supported by aryloxides.

Single-atom (group 15 and group 16 anions) bridged dimetallic complexes of low oxidation state uranium provide a convenient route to implement multielectron transfer and promote magnetic communication in uranium chemistry, but remain extremely rare. Here we report the synthesis, redox and magnetic properties of N 3- , O 2- , and S 2- bridged diuranium complexes supported by bulky aryloxide ligands. The U(IV)/U(IV) nitride [Cs(THF) 8 ][(U(OAr) 3 ) 2 (μ-N)], 1 could be prepared and characterized but could not be reduced. Reduction of the neutral U(IV)/U(IV) complexes [(U(OAr) 3 ) 2 (μ-X)] A (X = O) and B (X = S) led to the isolation and characterization of the U(IV)/U(III) and U(III)/U(III) analogues. Complexes [(K(THF) 4 ) 2 (U(OAr) 2 ) 2 (μ-S) 2 ], 5 and [K(2.2.2-cryptand)] 2 [(U(OAr) 3 ) 2 (μ-S)], 6 are the first examples of U(III) sulphide bridged complexes. Computational studies and redox properties allow the reactivity of the dimetallic complexes to be related to their electronic structure.