Synthesis and structure of K2[(UO2)4(O)2(OH)2(C2O4)(CH3COO)2(H2O)2]·2H2O

Single crystals of the compound K2[(UO2)4(O)2(OH)2(C2O4)(CH3COO)2(H2O)2]·2H2O (I) are synthesized, and their structure is investigated using X-ray diffraction. Crystals of compound I belong to the triclinic system with the unit cell parameters a = 7.6777(6) Å, b = 7.9149(7) Å, c = 10.8729(9) Å, α = 72.379(2)°, β = 86.430(3)°, γ = 87.635(2)°, V = 628.33(9) Å3, space group P\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \bar 1 $$\end{document}, Z = 1, and R1 = 0.0323. The main structural units of the crystals are [(UO2)4(O)2(OH)2(C2O4)(CH3COO)2(H2O)2]2− chains, which belong to the crystal-chemical group A4M23M22K02B201M21 (A = UO22+, M3 = O2−, M2 = OH−, K02 = C2O42−, B01 = CH3COO−, M1 = H2O) of the uranyl complexes. The chains are formed by linking the centrosymmetric tetramers of the composition (UO2)4(O)2(OH)2(CH3COO)2(H2O)2 via tetradentate bridging oxalate ions. The uranium-containing groups are joined into a three-dimensional framework through the electrostatic interaction with potassium cations and a system of hydrogen bonds, which are formed with the participation of atoms involved in the composition of the water molecules, hydroxide ions, and uranyl ions.