A New Tripodal Ligand System with Steric and Electronic Modularity for Uranium Coordination Chemistry.

The synthesis of a potentially redox active tripodal ligand containing a thri(aryloxide) functionalized mesitylene anchor, ((tBu'ArOH)3mes) (1), and its metatation with low-valent uranium to form [((tBu ArO)3mes)U] (1-U) is reported. The results from characterization by X-ray crystallography, spectroscopic studies, and computational analysis, as well as initial reactivity studies, support a+3 uranium oxidation state. Comparison to the previously synthesized complex, [((tBuArO)3tacn)U] (2-U), featuring the . redox-innocent Irtazacyctononane anchor reveals that changing the anchor from the flexible friazacydononane to a rigid mesilyl fragment increases the structural flexibility of the arylotdde substituents in complexes ott. The synthesis and crystal structures of uranium(IV) amide complexes of 1-U and 2-U are discussed. [ABSTRACT FROM AUTHOR]