Synthese und Struktur von Zn(HSO4)2(H2SO4)2 und Cd(HSO4)2 / Synthesis and Structure of Zn(HSO4)2(H2SO4)2 und Cd(HSO4)2

Abstract

Abstract From the binary systems M2SO4/H2SO4 (M = Zn, Cd), two new hydrogen sulfates, (Zn(HSO4)2(H2SO4)2 and Cd(HSO4)2, have been synthesized and structurally characterized. Both compounds crystallize in the monoclinic space group P21/c with cell parameters a = 5.047(2), b = 15.430(4), c = 7.958(3) Å and β = 104.16(4)° (Z= 2) for Zn(HSO4)2(H2SO4)2 and a = 5.339(1), b = 13.351(3), c = 8.508(2) Å and β = 92.22(3)° (Z = 4) for Cd(HSO4)2. In the zinc compound there are slightly distorted centrosymmetric ZnO6 octahedra with Zn-O distances of 2.05-2.13 A which are sharing corners with SO4 tetrahedra. HSO4 and H2SO4 tetrahedra are linked via hydrogen bonds to form layers perpendicular to the c-axis. In the crystal structure of Cd(HSO4)2 there exist two crystallographically different HSO4 tetrahedra. The CdO6 octahedra with Cd-O distances between 2.24 and 2.31 A are strongly angle-distorted. Besides hydrogen bonds of medium strength (do···o = 2.66 Å) there are also much more weaker ones (do···o = 3.04 Å). Considering these latter ones zigzag chains in z-direction can be recognized. The relatively low stability of Cd(HSO4)2 in comparison with other metal-II-hydrogen sulfates is discussed with respect to its structural pecularities.