Synthesis and Structure of Ag4Te(SO4) – a New Compound Featuring a Silver‐Telluride Framework

Tetrasilver telluride sulfate was obtained as a black air‐stable polycrystalline powder; its structure was determined from X‐ray powder diffraction data. The new compound crystallizes in the cubic space group P2₁3, with the unit cell parameter a = 8.6263(2) Å and Z = 4. The crystal structure of Ag₄Te(SO₄) is composed of a positively charged silver‐telluride three‐dimensional framework, in which the isolated tetrahedral SO₄^2– anions are embedded. The framework features an irregular coordination for tellurium atoms with a coordination number of six and manifold Ag–Ag contacts ranging from 2.99 to 3.14 Å. The distortion of the SO₄^2– anion as well as the interactions within the framework and between the framework and the SO₄^2– anions are analyzed with the help of the structural data, vibrational spectra, and band structure calculations.     

Crystal structure and two-level supramolecular organization of glycinium triiodide

Glycinium triiodide was synthesized and its crystal structure was determined. The crystal structure consists of alternating asymmetric triiodide anions characterized by Raman spectroscopy and glycinium cations. The cations and anions form dimers (GlyH)₂(I₃)₂via (N)H···O, (N)H···I, and (O)H···I hydrogen bonds. The dimers are further linked into chains by secondary I···I interactions between adjacent triiodide anions. The supramolecular structure of glycinium triiodide is discussed in comparison with polyiodides of various cations.

     

Reduction of the host cationic framework charge by isoelectronic substitution: synthesis and structure of Hg7Ag2P8X6 (X = Br, I) and Hg6Ag4P8Br6

The first compounds, Hg(7)Ag(2)P(8)X(6) (X = Br, I) and Hg(6)Ag(4)P(8)Br(6), featuring the partial isoelectronic substitution of Hg(2+) for Ag(1+) in mercury-pnicogen frameworks have been obtained and structurally characterized. The new compounds are the supramolecular assemblies built of the covalently bonded metal-pnicogen frameworks trapping guests of different complexity. The frameworks feature the perfect ordering of Hg(2+) and Ag(1+) cations and contain P(2)(4)(-) and P(6)(6)(-) phosphorus clusters. The substitution of Hg(2+) with Ag(1+) leads to the reduction in charge of the host cluster-containing cationic matrix and concomitant replacement of the monatomic X(-) guest by a lesser amount of the AgBr(3)(2)(-) anions.     

Trapping phosphate anions inside the [Ag4I] framework: Structure, bonding, and properties of Ag4I(PO4)

Orange-red Ag₄I(PO₄) crystallizes in the monoclinic system, space group P2₁/m (No. 11), with the unit cell dimensions a=9.0874(6) Å, b=6.8809(5) Å, c=11.1260(7) Å, β=109.450(1)°, and Z=4. The crystal structure is fully ordered; it comprises the silver-iodine three-dimensional positively charged framework hosting the tetrahedral PO₄³⁻ guest anions. The framework features high coordination numbers for iodine and manifold Ag-Ag bonds ranging from 3.01 to 3.46 Å. The Ag-Ag interaction is bonding, it involves silver 4d and 5s orbitals lying, together with the orbitals of iodine, just below the Fermi level. Though the orbitals of silver and iodine define the conducting properties of the title compound, the interaction between the framework and the guest anions is also important and is responsive to the number of the silver atoms surrounding the PO₄³⁻ tetrahedra. Ag₄I(PO₄) melts incongruently at 591 K and produces a mixture of the silver phosphate and an amorphous phase upon cooling. Pure Ag₄I(PO₄) is a poor conductor with a room temperature conductivity of 3×10⁻⁶ S m⁻¹. The discrepancies between the properties observed here and those reported previously in the literature are discussed.     

Synthesis and the crystal and electronic structure of Hg4AsI5

New mercury arsenide iodide Hg₄AsI₅ was synthesized and its crystal and electronic structure was determined. The crystal structure is layered. The layers are composed of alternating AsHg₄ tetrahedra and IHg₈ Archimedean antiprisms and are bound by the iodine atoms, which form short Hg-I bonds with all mercury atoms. Band structure calculations provided evidence for very weak interactions between the iodine atoms of the adjacent layers and the ionic character of the iodine atom centering the Archimedean antiprism. Hence, individual [AsHg₄I₄]⁺ clusters and I⁻ anions can be distinguished. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 736–739, May, 2006. Additional details of the crystal structure study (deposition number CSD-416238) can be obtained from the Fachinformationszentrum Karlsruhe, D-76344 Eggenstein-Leopoldshafen, Germany, fax: +(49)7247-808-666; e-mail: crysdata@fiz-karlsruhe.de.     

Synthesis and crystal structure of new double mercury silver phosphide iodide Hg<Subscript>12</Subscript>Ag<Subscript>41</Subscript>P<Subscript>88</Subscript>I<Subscript>41</Subscript>

New double mercury silver phosphide iodide Hg₁₂Ag₄₁P₈₈I₄₁ (1) was synthesized and its crystal structure was established. Compound 1 crystallizes in the cubic system. The characteristic feature of the crystal structure 1 is the presence of the anionic cage clusters P₁₁ ³⁻, which have been previously found in alkali metal compounds only. The well-ordered P₁₁ ³⁻ clusters form a system of polyhedra, which encapsulate various disordered α-AgI-type fragments. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1882–1886, October, 2007.     

Crystal structure of α-Ag<Subscript>8</Subscript>S<Subscript>3</Subscript>SO<Subscript>4</Subscript>

The crystal structure of silver sulfide-sulfate α-Ag₈S₃SO₄ was determined by X-ray powder diffraction data. The substance crystallizes in the tetragonal system and the space group P-4 with the unit cell parameters of α = 7.2032(4) Å, c = 5.1043(5) Å, Z = 1, R _f = 5.55%, χ² = 3.45. The layers in the structure of the compound formed by trigonal prisms of Ag₆S connected to each other through the vertices are connected by the additional atoms of sulfur into a three-dimensional framework. Distorted tetrahedral anions of SO ₄ ^2? are located in the cavities of the framework, the symmetry (D _2d ) of which was confirmed by the data of IR spectroscopy.     

Synthesis,structure, and properties of LnBiI<Subscript>6</Subscript>•13H<Subscript>2</Subscript>O (Ln = La,Nd)

Two new iodobismuthates with the composition LnBiI₆?13H₂O (Ln = La, Nd) were synthesized and their crystal structures were determined. The compound LaBiI₆?13H₂O crystalizes in the orthorhombic space group Pna2₁, a = 24.206(5), b = 8.405(1), c = 26.360(5) Å; the compound NdBiI₆?13H₂O crystalizes in the monoclinic space group P2₁/n, a = 14.553(3), b = 13.386(3), c = 27.541(6) Å, β = 92.80(3)°. In both crystal structures, the cations Ln(H₂O)₉³⁺ and the anions BiI₆^3– alternate, forming a NaCl-type structure, and the structures themselves differ in the arrangement of water of crystallization that leads to the formation of dissimilar systems of hydrogen bonds. Both compounds undergo decomposition when heated, which is accompanied first by a partial liberation of water molecule, followed by pyrohydrolysis to form oxoiodides LnOI as final solid products. According to optical measurements, the band gap of the obtained compounds was equal to 1.78 (La) and 1.71 (Nd) eV.