Zur Struktur der basischen Diquecksilber(I)-nitrate. III. Kristallstruktur des Hg4O2(NO3)2

Crystal Structure of the Basic Dimercury(I) Nitrates. III. Crystal Structure of Hg₄O₂(NO₃)₂ Hg₄O₂(NO₃)₂ crystallizes monoclinic, space group P2₁/a – standard setting P2₁/c (C) – with a = 1158.0(2), b = 666.4(1), c = 553.3(1) pm, β = 98.82(1)° and Z = 2. The structure determination from single crystal diffractometer data (AgKα, 1170 I₀(hkl), numerical absorption corrections applied) resulted in a final R = 0.0512 (R_w = 0.0685). The mixed valence compound is built up of puckered layers (Hg^II)_2/2O(Hg)_1/2]⁺ parallel (201). Within the layers there are exclusively covalent Hg? Hg and Hg? O bonds; whereas the linkage between the layers is achieved by weak Hg^I? O contacts and by nitrate ions functioning as weak bridging ligands for mercury atoms. This layer structure explains the distinct cleavage of crystals of Hg₄O₂(NO₃)₂.