Structures of homoleptic eight- and nine-coordinate uranium(IV) perchlorate complexes with sulfoxide molecules as ligands

Homoleptic eight- and nine-coordinate U(IV) perchlorate complexes, [U(dmso)8](ClO4)4 · 0.75CH3NO2(a), [U(dmso)9](ClO4)4 · 4dmso (b) (dmso = dimethyl sulfoxide), and [U(tmso)8]ClO4)4 · 2tmso (c) (tmso = tetramethylene sulfoxide) have been prepared and characterized crystallographically. Complexes a, b, and c have dodecahedral, tricapped trigonal prismatic, and square antiprismatic geometries, respectively. Spectrophotometric studies clarified that [U(dmso)8]4+ is in equilibrium with [U(dmso)9]4+ in CH3NO2 solution containing dmso.