Synthesis and reactivity of uranium(IV) amide complexes supported by a triamidotriazacyclononane ligand

Reaction of [U{(SiMe2NPh)(3)-tacn}Cl] with LiNEt2 or LiNPh2 affords the corresponding amide compounds, [U{(SiMe2NPh)(3)-tacn}(NR2)] (R = Et (1), R = Ph (2)). The complexes have been fully characterized by spectroscopic methods and the solid- state structure of 1 was determined by single-crystal X-ray diffraction analysis. The six nitrogen atoms of the tris(dimethylsilylanilide)triazacyclononane ligand are in a trigonal prismatic con. guration with the nitrogen atom of the diethylamide ligand capping one of the trigonal faces of the trigonal prism. Crystallization of 2 from CH3CN solution gave crystals of the six-membered heterocycle [U{(SiMe2NPh)(3)-tacn}{kappa(2)-(HNC(Me))(2)CC equivalent to N}] (3). The reactivity of the amides was investigated. Both compounds undergo acid-base reactions with protic substrates such as HOC6H2-2,4,6-Me-3, 3,5-Me(2)pzH (pz = pyrazolyl) and HSC5H4N to give the corresponding [U{(SiMe2NPh)(3)-tacn}X] (X = OC6H2-2,4,6-Me-3 (4), 3,5-Me(2)pzH (5), kappa(2)-SC5H4N (6)) complexes. The solid- state structures of 3 and 6 were determined by single-crystal X-ray diffraction and revealed that the compounds are eight-coordinate with dodecahedral geometry.