Volker Krämer

The crystal structure of Bi4O5I2 and its relation to the structure of Bi4O5Br2

Abstract The crystal structure of Bi4O5I2 has been solved from a 3:1 twinned crystal; accurate lattice parameters have been determined by a Rietveld refinement. Bi4O5I2 crystallizes with space group P21 (no. 4), Z=4, a=14.944(1), b=5.6983(3), c=11.263(1) Å, β= 99.81(1)°. Its structure is isotypic to the structure of the homologous Bi4O5Br2 for which more reliable lattice parameters have been determined by a Rietveld refinement. The effects of replacement of Br by I on the structure are discussed and compared with corresponding effects in the BiOX family (X = Cl, Br, I). A structural reason for the deviation of the twin supercells of the two compounds from orthogonality is discussed.

Redetermination of the crystal structures of the `Arppe compound' Bi24O31Cl10 and the isomorphous Bi24O31Br10

The crystal structures of Bi24O31X10 (X = Cl, Br; 24-bismuth 31-oxide decachloride/-bromide) have been redetermined. The structure models obtained resemble the model described in the literature about 60 years ago, but differ from it in some details of the O substructure and in the fact that the structure for X = Cl is a twofold superstructure of the literature model. A fictional mechanism is given by which the formerly described incorrect O substructure is transferred into the correct one.

The crystal structure of α-Bi5O7I

Abstract The structure of α-Bi5O7I, synthesized by the addition of a diluted H[BiI4] solution to 5N KOH, has been determined. α-Bi5O7I crystallizes with space group Ibca, Z=8, a=16.265(2), b=5.3439(6), c=23.020(3) Å. It shows a close relationship to the structure of BiOI. The chemical reaction which leads to the synthesis of α-Bi5O7I is discussed in the light of this relationship.

A Strong Deviation from Vegard's Rule: X-Ray Powder Investigations of the Three Quasi-Binary Phase Systems BiOX-BiOY (X, Y = Cl, Br, I)

The three quasi-binary phase systems BiOX-BiOY (X, Y = Cl, Br, I) have been investigated by X-ray powder methods. No quaternary phases were found in the three systems. BiOCl-BiOBr and BiOBr-BiOI form systems of unlimited mutual solubility. BiOCl-BiOI is a system of limited solubility at the iodine-rich side. In the BiOBr-BiOI system a strong deviation from Vegard’s rule is observed with respect to one of the lattice parameters. A few methods to quantify such a deviation are briefly discussed and a possible explanation for the strong deviation in the BiOBr-BiOI system is proposed. Error calculations have been performed to estimate uncertainties in the concentration parameter x of the investigated mixtures. The crystal structure of BiOI has been re-determined by single crystal structure analysis.

Crystal structure and twinning of Bi4O5Br2

Abstract The monoclinic crystal structure of Bi4O5Br2 has been determined from 1:1 twinned crystals pretending orthorhombic symmetry. Bi4O5Br2 crystallizes with space group P21 (no. 4), Z=4, a=14.539(4), b=5.605(1), c=10.782(3) Å, β= 97.75(7)°. Its structure shows much closer relationships to the structure of α-Bi5O7I than to that one of the homologuous compound Bi4O5Cl2.

Crystal structure and twinning of KCd4Ga5S12 and some isotypic AB4C5X12 compounds

Nine new compounds of composition AB 4 C 5 X 12 with distinct elements being among A: K, Rb, Cs; B: Zn, Cd; C: Ga; X: S, Se, Te were prepared by solving ZnGa 2 S 4 , CdGa 2 S 4 , ZnGa 2 Se 4 , CdGa 2 Se 4 , and CdGa 2 Te 4 in KBr, RbBr, and CsBr, respectively. The crystal structure of KCd 4 Ga 5 S 12 was solved and refined to R = 0.03. It crystallizes with space group R3, the hexagonal lattice parameters being a 0 = 13.782(3) A and c 0 = 9.330(3) A [rhombohedral setting: a 0 = 8.543(2) A, α = 107.53(1)°], and shows a thirteenfold superstructure. KCd 4 Ga 5 S 12 consists of a cubic close packing of sulfur atoms with partially ordered Cd and Ga cations in the tetrahedral interstices. The potassium ion substitutes one sulfur atom and is located inside a cubooctahedral interstice of the sulfur sublattice

Vapour growth and structural characterization of the new indium bismuth sulphide halides InBi2S4Cl and InBi2S4Br

The title compounds were prepared for the first time, and ledge-shaped single crystals were grown by chemical vapour transport. InBi2S4Cl(Br) crystallizes in the space group C2m with lattice parameters a = 12.383 (12.55), b = 3.899 (3.90), c = 8.514 (8.58)A, and β = 115.30 (115.2)°; Z = 2. The crystal structure of InBi2S4Cl was determined from 816 independent reflexions and refined to R = 4.0%. The indium atoms occupy the center of distorted sulphur octahedra which are linked to chains running in y-direction. They are interconnected by bands of bismuth and chlorine atoms. Bismuth is irregularly surrounded by six sulphur and two chlorine atoms.

Crystal Structure of the Trihydrate of the Neuraminidase Inhibitor C15H28N4O4 (Peramivir), a Potential Influenza A/B and Avian-influenza (H5N1) Drug

The crystal structure of the trihydrate of peramivir (C15H28N4O4), a potential influenza A/B and avian-influenza drug, has been determined. The structure, belonging to the tetragonal space group P42212 with Z = 32, a = 27.216(4), c = 23.084(5) Å, V = 17098(5) Å3, contains four organic molecules plus 12 partially disordered water molecules per asymmetric unit. 16 Organic molecules per unit cell form a kind of 1D infinite micelle separated from vicinal micelles by approximately planar water layers. During exposure to X-rays or under long-time storage on air peramivir trihydrate undergoes a phase transition to a structurally closely related phase with reduced water contents.