Molten salt flux synthesis and structure of the new layered uranyl tellurite, K4[(UO2)5(TeO3)2O5]

The reaction of UO3 and TeO3 with a KCl flux at 800 °C for 3 days yields single crystals of K4[(UO2)5(TeO3)2O5]. The structure of the title compound consists of layered, two-dimensional ∞2[(UO2)5(TeO3)2O5]4- sheets arranged in a stair-like topology separated by potassium cations. Contained within these sheets are one-dimensional uranium oxide ribbons consisting of UO7 pentagonal bipyramids and UO6 tetragonal bipyramids. The ribbons are in turn linked by corner-sharing with trigonal pyramidal TeO3 units to form sheets. The lone-pair of electrons from the TeO3 groups are oriented in opposite directions with respect to one another on each side of the sheets rendering each individual sheet nonpolar. The potassium cations form contacts with nearby tellurite units and axial uranyl oxygen atoms. Crystallographic data (193 K, MoK  α, λ=0.71073Å): triclinic, space group P1¯, a=6.8514(5)Å, b=7.1064(5)Å, c=11.3135(8)Å, α=99.642(1)°α=99.642(1)°, β=93.591(1)°β=93.591(1)°, γ=100.506(1)°γ=100.506(1)°, V=531.48(7)Å3, Z=1,R(F)=4.19%Z=1,R(F)=4.19% for 149 parameters and 2583 reflections with I>2σ(I)I>2σ(I).

Graphical abstractAn illustration of the ∞2[(UO2)5(TeO3)2O5]4- sheets in K4[(UO2)5(TeO3)2O5]. The one-dimensional uranium oxide ribbons extend along the b-axis and consist of corner-sharing pentagonal bipyramidal UO7 units and UO6 tetragonal bipyramids. The chains are linked by trigonal pyramidal TeO3 units, shown in ball-and-stick form, to form sheets.Figure optionsDownload full-size imageDownload as PowerPoint slide