Structure and some properties of UO2(C2H5COO)2 · nQ · mH2O (Q is carbamide or ethylenecarbamide)

Abstract

The crystals of [UO₂(C₂H₅COO)₂(CO(NH₂)₂)₂] · H₂O (I) and [UO₂(C₂H₅COO)₂(H₂O)₂] · 2C₃H₆N₂O (II), where CO(NH₂)₂ is carbamide, C₃H₆N₂O is ethylenecarbamide, were synthesized and studied by IR spectroscopy and X-ray diffraction. The key structural units of compounds I are II are mononuclear electrically neutral complexes, which belong to the AB⁰¹M₃¹ and AB⁰¹M₂¹ crystal-chemical groups (A = UO2²⁺ B⁰¹ = C₂H₅COO^–; M¹ = C₂H₅COO^– or CO(NH²)² (I), H²O (II)) of uranyl complexes. The factors that affect the “selection” of the coordination number of U(VI) atoms (7 or 8, respectively) in the crystal structures of I and II and, as a consequence, are responsible for different structures of uranium complexes are discussed.