A Complete Family of Terminal Uranium Chalcogenides, [U(E)(N{SiMe_3}_2)_3]~- (E = 0, S, Se, Te)

摘要

Addition of 1 equiv of E (E = 0.125 S_8, Se, Te) to U(H_2C=PPh_3)(NR_2)_3 (R = SiMe_3) (1) in Et_2O results in generation of the terminal chalcogenide complexes, [Ph_3PCH_3][U(E)(NR_2)_3] (E = S, 2; Se, 3; Te, 4; R = SiMe_3), in modest yield. Complexes 2-4 represent extremely rare examples of terminal uranium monochalcogenides. Synthesis of the oxo analogue, [Cp_2~*Co][U(O)(NR_2)_3] (5), was achieved by reduction of [U(O)(NR_2)_3] with Cp_2~*Co. All complexes were fully characterized, including analysis by X-ray crystallography. In the solid state, complexes 2-5 feature short U-E bond lengths, suggestive of actinide-ligand multiple bonding.