(NH₄)₂[UO₂Cl₄]·2H₂O, a new uranyl tetrachloride with ammonium charge-balancing cations

Abstract

A new uranyl tetrachloride salt with chemical formula, (NH4)2[UO2Cl4]·2H2O, namely, diammonium uranyl tetrachloride dihydrate, 1, was prepared and crystallized via slow evaporation from a solution of 2 M hydrochloric acid. As confirmed by powder X-ray diffraction, the title compound crystallizes with an ammonium chloride impurity that formed as a result of the breakdown of a triazine precursor. The (UO2Cl4)2− dianion is charge balanced by ammonium cations, while an extensive hydrogen-bond network donated from structural water molecules stabilize the overall assembly. Compound 1 adds to the extensive collection of actinyl tetrachloride salts, but it represents the first without an alkali cation for purely inorganic compounds. Diffuse reflectance and luminescence spectra show typical absorption and emission behavior, respectively, of uranyl materials.