Tetrahedra and vertex-sharing double tetrahedra in the ammonium iodomercurates(II) (NH4)(7)[HgI4](2)[Hg2I7](H2O) and (NH4)(3)[Hg2I7]

The new ammonium iodomercurates(II), (NH4)(7)[HgI4](2)[Hg2I7](H2O) (1) and (NH4)(3)[Hg2I7] (2) contain isolated tetrahedra and vertex-sharing double tetrahedra as the anions. The crystal structures were determined from single-crystal X-ray diffraction data: 1: orthorhombic, Pnma (no. 62), a = 2175.9(2), b = 1781.8(2), c = 1256.2(2) pm, Z = 4. R-1 [I-0 > 2 sigma(I-0)] = 0.0520; 2: monoclinic, P2(1)/c (no. 14), a = 1259.0(2), b = 773.2(1), c = 2172.4(3) pm, beta = 101.18(2)degrees, Z = 4, R, [I-0 > 2 sigma(I-0)] = 0.0308.