Effects of ionic liquid media on the cation selectivity of uranyl structural units in five new compounds produced using the ionothermal technique

Abstract

Ionothermal reactions of uranyl salts in several ionic liquids containing cyclic cations produced single crystals of five new uranyl compounds. (C₄H₇N₂)[(UO₂)(AsO₄)] (1), (C₈H₁₅N₂)₂[(UO₂)₄(SeO₃)₅] (2), (C₆H₁₁N₂)₂[(UO₂)₃(C₂H₅PO₄)₄] (3), and (C₅H₅N)₂[(UO₂)₂(SeO₄)₃] (4) are each comprised of two-dimensional structural units. (C₄H₇N₂)[(UO₂)₅(PO₄)₃(HPO₄)(H₂O)₂]·3H₂O (5) is composed of a three-dimensional network. While the uranyl structural units in all five compounds are directly related to ones found in either uranyl minerals or compounds produced in aqueous media, each contain cyclic ionic liquid constituents as charge-balancing agents. These results suggest that the cation selectivity of these structural units is low, even under various solvation conditions and templating effects from cyclic cations donated from ionic liquid media.