Intra- and intermolecular interception of a photochemically generated terminal uranium nitride

The photochemically generated synthesis of a terminal uranium nitride species is here reported and an examination of its intra- and intermolecular chemistry is presented. Treatment of the U(iii) complex L(Ar)UI(DME) ((L(Ar))(2−) = 2,2′′-bis(Dippanilide)-p-terphenyl; Dipp = 2,6-diisopropylphenyl) with LiNIm(Dipp) ((NIm(Dipp))(−) = 1,3-bis(Dipp)-imidazolin-2-iminato) generates the sterically congested 3N-coordinate compound L(Ar)U(NIm(Dipp)) (1). Complex 1 reacts with 1 equiv. of Ph(3)CN(3) to give the U(iv) azide L(Ar)U(N(3))(NIm(Dipp)) (2). Structural analysis of 2 reveals inequivalent N(α)–N(β) > N(β)–N(γ) distances indicative of an activated azide moiety predisposed to N(2) loss. Room-temperature photolysis of benzene solutions of 2 affords the U(iv) amide (N-L(Ar))U(NIm(Dipp)) (3) via intramolecular N-atom insertion into the benzylic C–H bond of a pendant isopropyl group of the (L(Ar))(2−) ligand. The formation of 3 occurs as a result of the intramolecular interception of the intermediately generated, terminal uranium nitride (L(Ar))U(N)(NIm(Dipp)) (3′). Evidence for the formation of 3′ is further bolstered by its intermolecular capture, accomplished by photolyzing solutions of 2 in the presence of an isocyanide or PMe(3) to give (L(Ar))U[NCN(C(6)H(3)Me(2))](NIm(Dipp)) (5) and (N,C-L(Ar)*)U(N[double bond, length as m-dash]PMe(3))(NIm(Dipp)) (6), respectively. These results expand upon the limited reactivity studies of terminal uranium–nitride moieties and provide new insights into their chemical properties.