Serendipitous formation and characterization of K2[Pd(NO3)4]·2HNO3

A potassium tetranitratopalladate(II) with the composition K2[Pd(NO3)4] · 2HNO3 was synthesized by a simple solvothermal process in a glass ampoule. The new compound crystallizes in the monoclinic space group P21/c (no. 14) with the lattice parameters a = 1017.15(4), b = 892.94(3), c = 880.55(3) Å, and β = 98.13(1)° (Z = 2). The crystal structure of K2[Pd(NO3)4] · 2HNO3 reveals isolated complex [Pd(NO3)4]2− anions, which are surrounded by eight potassium cations and four HNO3 molecules. The complex anions and the cations are associated in layers which are separated by HNO3 molecules. K2[Pd(NO3)4] · 2HNO3 can thus be regarded as a HNO3 intercalation variant of β-K2[Pd(NO3)4]. The characterization is based on single-crystal X-ray and powder X-ray diffraction.

Hydrogenium-bis-hydrogensulfate anions adjacent to [S2O7]2− in Rb3[S2O7][H(HSO4)2]: a structural evidence of the increasing acidity of polysulfuric acids with growing chain length

Rb3[H(HSO4)2][S2O7] (monoclinic, C2/c (no. 15), a=1638.75(6), b=768.52(3), c=1187.88(4) pm, β=106.805(2)°, V=1432.14(9)·106 pm, Z=4) was obtained from the reaction of Rb2[CO3] (99.9%, not dried, 150 mg, 0.6 mmol) with neat SO3 in a torch-sealed glass ampoule. The remaining quantity of water in the starting material was obviously sufficient to lead to an H-containing substance. The structure shows the unprotonated disulfate anion [S2O7]2− adjacent to the hydrogenium-bis-hydrogensulfate anion [H(HSO4)2]− with the central hydrogen atom located close to a center of inversion.