PNNL

Abstract

We report the synthesis and characterization of substituted arylsilylamide ligands and their respective bisamido complexes of U(III), (3,5-R2-PhMe2SiNDipp)2UI(dioxane)x (1, R = H, x= 0; 2, R = Me, x = 0; 3, R = tBu, x =1). We found that the steric bulk of 3,5-R2-Ph ring affects the hapticity of the arene to U. In the solid-state 1 is an U-(?6-arene) complex, while 2 is an U-(?1-arene) complex. Theoretical calculations of the delocalization indices, Wiberg bond orders, Mayer bond orders and fuzzy bond orders at PBE0 and PBE0-D3 levels of theory support these hapticity assignments. The 3,5-tBu2-Ph rings of 3 are too bulky to interact with U and solid-state metrical parameters initially suggested an U-(?1-arene) interaction with one of the Dipp rings. However, bond order calculations show there is no significant interaction, and 3 is best described as an U-(?0-arene) complex. U-(?6-arene) U-(?1-arene) NBO DATA Surprisingly, attempts to generate (3,5-R2-PhMe2SiNPh)2UI complexes results in oxidative metalation to the homoleptic tetraamido (3,5-R2-PhMe2SiNPh)4U(IV) (4, R = H; 5, R = Me) complexes.