Stepwise Reduction of Dinitrogen by a Uranium–Potassium Complex Yielding a U(VI)/U(IV) Tetranitride Cluster

Multimetallic cooperativity is believed to play a key role in the cleavage of dinitrogen nitrides (N3-), but mechanism remains ambiguous due lack isolated intermediates. Herein, we report reduction complex [K2{[UV(OSi(OtBu)3)3]2(?-O)(?-?2:?2-N2)}], B, with KC8, yielding tetranuclear tetranitride cluster [K6{(OSi(OtBu)3)2UIV}3{(OSi(OtBu)3)2UVI}(?4-N)3(?3-N)(?3-O)2], 1, novel example N2 nitride by diuranium complex. The structure 1 remarkable, as it contains unique uranium center bound four and provides second trans-N?UVI?N core analogue UO22+. Experimental computational studies indicate that formation U(IV)/U(VI) tetrauranium occurs via successive one-electron transfers from potassium N24- ligand resulting putative diuranium(V) bis-nitride [K4{[UV(OSi(OtBu)3)3]2(?-O)(?-N)2}], X. Additionally, cooperative binding U-bound facilitates during electron transfer. nucleophilic both complexes are easily functionalized protons yield ammonia 93-97% excess 13CO K13CN KN13CO. structures two U(IV)/U(V) bis- mononitride clusters reaction CO demonstrate moieties replaced oxides without disrupting structure, ultimately leading valence redistribution.