Metal Hexaammine as a Bulky Cation: Structural and Property Studies of [M(NH3)6]Cu8Sb3S13 (M = Mn, Fe, Ni) and [Fe(NH3)6]AgES4 (E = As, Sb)

Abstract

Five new compounds, which bring together two classical groups, Werner transition-metal hexaammine complexes and sulfosalts, have been prepared from supercritical ammonia. They form in two different structure types which are built from traditional octahedrally coordinated transition-metal hexaammine cations and anionic networks that can be described as metalated derivatives of sulfosalts. The anionic framework of compound I, [Fe(NH3)6]Cu8Sb3S13, is built around a central Cu8S13 core in which copper atoms are surrounded by sulfur atoms in a very distorted tetrahedral coordination. These copper sulfide cores are linked together through bridging antimony atoms which assume a very regular tetrahedral coordination of sulfur atoms. The three mutually orthogonal channels created by the anion are filled with Fe(NH3)6 cations. In [Fe(NH3)6]AgES4 (E = Sb or As), II and III, respectively, the anionic framework is a one-dimensional chain built from alternating E− and Ag−sulfide tetrahedra that share opposite edges. In this structure type, hydrogen bonding apparently plays a role in the packing of the Fe(NH3)6 cations and anionic chains. Substitution of Fe with Mn or Ni in the synthesis results in compounds with the structure type observed in I. The synthetic routes and characterization, via X-ray crystallography, Mössbauer and IR spectroscopies, DSC, TGA, and bond valence sums are described. Crystal data: I, black cube, F4̄3c, a = 17.800(2) Å, V = 5640(1) Å3, Z = 8, R (wR) = 0.0432 (0.0472); II, yellow parallelepiped, P4̄n2, a = 10.274(2) Å, c = 6.707(2) Å, V = 707.9(3) Å3, Z = 2, R (wR) = 0.0249 (0.0297); III, yellow polyhedron, P4̄n2, a = 10.244(2) Å, c = 6.660(2) Å, V = 698.8(3) Å3, Z = 2, R (wR) = 0.0372(0.0423).