(NH 4 ) 2 [UO 2 Cl 4 ]·2H 2 O, a new uranyl tetra-chloride with ammonium charge-balancing cations.

A new uranyl tetra-chloride salt with chemical formula, (NH 4 ) 2 [UO 2 Cl 4 ]·2H 2 O, namely, di-ammonium uranyl tetra-chloride dihydrate, 1 , was prepared and crystallized via slow evaporation from a solution of 2 M hydro-chloric 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 (UO 2 Cl 4 ) 2- dianion is charge balanced by ammonium cations, while an extensive hydrogen-bond network donated from structural water mol-ecules stabilize the overall assembly. Compound 1 adds to the extensive collection of actinyl tetra-chloride 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.