Synthesis and structure of crystals of UO2(C2H5COO)2·1.5L (L = methylurea or N,N’-dimethylurea)

Resumo

The compounds UO₂(C₂H₅COO)₂·1.5L, where L is methylurea (Meur) or N,N’-dimethylurea (s-Dmur), were synthesized and studied by IR spectroscopy and single crystal X-ray diffraction. Irrespective of the kind of amide L, the structure of the compounds consists of two mononuclear uranium-containing complexes: cationic [UO₂(prop)L₃]⁺ and anionic [UO₂(prop)₃]^–, where prop is propionate ion. Both compounds belong to crystal-chemical group AB⁰¹M₃¹+ AB⁰¹M₃⁰¹ (A = UO₂²⁺, B⁰¹ = prop^–, M¹ = L) of uranyl complexes. The composition of 15 stable uranyl complexes that can be formed in the UO₂²⁺, B⁰¹–prop^––L–H₂O system was predicted on the basis of the characteristics of the Voronoi–Dirichlet polyhedra from the standpoint of the 18-electron rule.