Synthesis and X-ray structural investigation of (C3N6H7)4(CN3H6)2[UO2(CrO4)4] · 4H2O and (H3O)6[UO2(CrO4)4]

Single crystals of the compounds (C3N6 H7)4(CN3H6)2[UO2(CrO4)4] · 4H2O (I) and (H3O)6[UO2(CrO4)4] (II) are synthesized, and their structures are investigated using X-ray diffraction. Compound I crystallizes in the triclinic system with the unit cell parameters a = 6.3951(8) Å, b = 10.8187(16) Å, c = 16.9709(18) Å, α = 93.674(4)°, β = 97.127(4)°, γ = 92.020(4)°, 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, V = 1161.6(3) Å3, and R = 0.0470. Crystals of compound II belong to the monoclinic system with the unit cell parameters a = 14.3158(4) Å, b = 11.7477(3) Å, c = 13.1351(4) Å, β= 105.836(1)°, space group C2/c, Z = 4, V = 2125.2(1) Å3, and R = 0.0213. The uranium-containing structural units of crystals I and II are mononuclear anionic complexes of the composition [UO2(CrO4)4]6− with an island structure, which belong to the crystal-chemical group Am14 (A = UO2+2, M1 = CrO2−4) of the uranyl complexes. The [UO2(CrO4)4]6− anionic complexes are joined into a three-dimensional framework through the electrostatic interactions with outer-sphere cations and a system of hydrogen bonds.