Uranium(III) scorpionates:: Synthesis and structure of [(TPMe2)2U{N(C6H5)2}] and [(TpMe2)2U{N(SiMe3)2}]

Reaction of [(Tp(Me2))(2)Ul] with KNR2 (R = C6H5, SiMe3) in tetrahydrofuran (THF) afforded the monomeric trivalent actinide amide complexes [(Tp(Me2))(2)U{N(C6H5)(2)}], 1, and [(Tp(Me2))(2)U{N(SiMe3)(2)}], 2. The complexes have been fully characterized by spectroscopic methods and their structures were confirmed by X-ray crystallographic studies. In the solid state 1 and 2 exhibit distorted pentagonal bipyramidal geometries. The U-NR2 bond lengths in both complexes are the same but in complex 2 the greater steric demands of the N(SiMe3)(2) ligand led to elongated U-N(pz) bonds, especially those opposite the amido ligand.