Flux crystal growth and structural analysis of two cesium uranium oxides, Cs2.2U5O16 and Cs2U4O13, containing multiple cation–cation interactions

Abstract

Single crystals of Cs_2.2U₅O₁₆ and Cs₂U₄O₁₃ have been synthesized from a CsCl flux with the ramp rate controlling the formation of fully oxidized Cs₂U₄O₁₃versus partially reduced Cs_2.2U₅O₁₆. Their structures have been determined by single crystal X-ray diffraction. Cs_2.2U₅O₁₆ crystallizes in the monoclinic space group C2/m with lattice parameters a = 13.4160(5) Å, b = 15.5089(6) Å, c = 7.9723(3) Å, and β = 92.7120(10)° and Cs₂U₄O₁₃ crystallizes in the orthorhombic space group Ccmm with lattice parameters a = 13.5031(6) Å, b = 15.4048(7) Å, c = 39.5680(17) Å. The two compounds contain related uranium frameworks with disordered Cs atoms within the channels. Both structures contain multiple cation–cation interactions, CCIs, which arise due to the three dimensional nature of the framework. Magnetic properties are reported for Cs_2.2U₅O₁₆, which contains mixed valent U.