B. A. Popovkin

The structure and bonding of Ni3Sn

Abstract The electronic structure of Ni3Sn was calculated at ab initio levels for the crystal structure of the low-temperature modification of Ni3Sn refined upon data of single-crystal X-ray diffractometry (P63/mmc, a=5.2950(7), c=4.247(1) A, R=0.0288). The calculations were made with the use of fixed Gaussian (CRYSTAL98 software) and energy-dependent (Stuttgart TB-LMTO-ASA software) basis sets. Difference electron charge density maps were analysed and compared with that of a hypothetical hcp Ni in order to understand bonding in Ni3Sn. It was found that bonding in Ni3Sn has multicentre character with Ni–Sn interaction stronger than Ni–Ni one.

New representative of Bi95+-containing phases: synthesis and crystal structure of the NbIV-containing Bi10Nb3Cl18 compound

The Bi10Nb3Cl18 compound was prepared using the high-temperature ampoule method, and its crystal structure was determined by single-crystal X-ray diffraction. This phase contains the Bi95+ cluster polycations and Bi+ cations surrounded by the NbCl62– complex anions. The latter contain the paramagnetic central NbIV ions, as evidenced by magnetic measurements.

Structural characterization of lead (II) oxybromide Pb3O2Br2

Abstract The lead (II) oxybromide Pb 3 O 2 Br 2 has been prepared by solid state reaction between PbO and PbBr 2 and its structure has been characterized by means of X-ray powder diffraction. The compound is crystallized in the orthorhombic system in space group Pnma, the lattice constance are: a = 12.252(3), b = 5.873(1), c = 9.815(3) A. The structure of Pb 3 O 2 Br 2 is built up of the distorted edgeshared [Pb 4 O] tetrahedra forming the doubled infinite chains parallel to [010]. These chains are mutually connected by Br atoms. A comparison with other Pb 3 O 2 X 2 (X = Cl, I) substances is presented.

New subvalent bismuth telluroiodides incorporating Bi2 layers : the crystal and electronic structure of Bi2TeI

Two new subvalent bismuth telluroiodides, Bi2TeI and Bi4TeI1.25, were prepared by the gas-phase synthesis. The compositions of these phases were determined by energy-dispersive X-ray spectroscopy. X-ray diffraction study of melt grown Bi2TeI single crystals demonstrated that the compound crystallizes in the monoclinic system (space group C/2m) with the unit cell parameters a = 7.586(1) Å, b = 4.380(1) Å, c = 17.741(3) Å, β = 98.20°. The layered crystal structure of Bi2TeI consists of weakly bonded two dimensional blocks with a stoichiometry of the title compound. The blocks are stacked along the c axis. Each block consists of eight atomic layers alternating in the Te-Bi-I-Bi-Bi-I-Bi-Te order and includes a double layer of bismuth atoms. Based on the results of ab initio quantum-chemical calculations, the title compound is expected to possess a pronounced anisotropy of conductivity.

The crystal structure of Hg7Sb4Br6

Abstract The crystal structure of Hg 7 Sb 4 Br 6 (previously reported as HgSbBr) has been solved by the X-ray single crystal technique. Hg 7 Sb 4 Br 6 crystallizes in the cubic system, space group Pa 3, Z = 4, with cell dimensions a = 12.9940(9)A. The structure consists of the three-dimensional positively charged [Hg 6 Sb 4 ] 4+ shell, and octahedral [HgBr 6 ] 4− anions. The antimony atoms in the shell are bound into Sb 4− 2 dumbells with short SbSb distance of 2.77 A. The possible migration of Hg 2+ ions along the fourfold axis is suggested.

A new family of supramolecular complexes with 3D cationic Hg/Z frameworks, SnX3- guest anions (Z = P, As, Sb; X = Cl, Br, I): Crystal structures and host-guest interactions

Five new inorganic supramolecular complexes, [Hg6P4Cl3](SnCl3) (I), [Hg6As4Cl3](SnCl3)Hg0.13 (II), [Hg6As4Br3](SnBr3) (III), [Hg6Sb4I3](SnI3)Hg0.16 (IV), and [Hg7P4Br3](SnBr3) (V), have been prepared and their structures determined by X-ray single crystal experiments. They all crystallize in the cubic space group P213 (No 198) with Z = 4, and unit cell parameters a = 11.865(1) (I), 12.233(1) (II), 12.383(1) (III), 13.285(2) (IV), and 12.490(1) A (V). The crystal structures of these compounds are composed of the 3D positively charged frameworks [Hg6Z4X3]+ (I−IV) or [Hg7P4Br3]+ (V), with SnX3− anions trapped in the larger cavities of the frameworks (X = Cl, Br, I; Z = P, As, Sb). In the structures of II and IV the smaller cavities are partly filled by mercury atoms. The structures of I−V and of previously reported [Hg7As4I3](SnI3) (VI) are discussed with respect to the matching and mutual adjusting of the host frameworks and guest anions. A comparison of the observed and calculated (ab initio, RHF level) geometry of the SnX3− anions is used to analyze the weak host−guest interactions.

New polymolecular bismuth monohalides. Synthesis and crystal structures of Bi4BrxI4-x (x = 1, 2, or 3)

New mixed bismuth monohalides Bi4BrxI4–x (x = 1, 2, or 3) were prepared for the first time by the reactions of bismuth metal with bismuth trihalides taken in stoichiometric amounts. Their crystal structures were established by single-crystal X-ray diffraction analysis. The Bi4Br3I and Bi4BrI3 compounds are isostructural and crystallize in the orthorhombic system, and Bi4Br2I2 crystallizes in the monoclinic system. The crystal structures of all three phases contain one-dimensionally infinite molecular chains consisting of the [Bi4X4] fragments whose structures are identical with those of the individual Bi4I4 and Bi4Br4 molecules. The molecules are packed in layers. Different packing modes of the layers were found for different bismuth monohalides. The Bi4ClI3 compound, which is apparently structurally similar to Bi4Br3I and Bi4BrI3, was also prepared.

[Hg7As4I3](SnI3): Trapping the SnI31- anion in the cavities of the unprecedented mercury-arsenic-iodine network

A novel host–guest compound [Hg7As4I3](SnI3) has been prepared by a standard ampoule technique and its crystal structure was determined. It crystallizes in a cubic system [space group P213, a = 13.110(1) A, Z = 4] with a unique structure type. The crystal structure comprises two parts: the three-dimensional [Hg7As4I3]1+ host network, and the SnI31– guest anions encapsulated in the cavities of the network. The network is built from the As2Hg7 bitetrahedra and As2Hg6 octahedra, which share corners, and contains an additional iodine atom connected to one of the mercury vertices. The SnI31– anion has the shape of a pyramid with the tin atom in a vertex. According to the quantum-chemistry calculations, the geometry of the anion deviates substantially from the equilibrium one, and is influenced by the distant mercury atoms of the host network.

Crystal and electronic structure of Ni3Bi2S2 (parkerite)

The crystal structure of parkerite, Ni3Bi2S2, was studied by single-crystal X-ray diffraction analysis and refined. The single crystal was prepared by the method of chemical transport reactions. The electronic structure of Ni3Bi2S2 was calculated by the extended Hückel and DFT--LMTO--ASA methods. Substantial delocalization of electrons in the vicinity of the Fermi level and the presence of the strong Ni--S and Ni--Bi bonds were revealed. The Ni--Ni bonds are weak, which is in agreement with the X-ray diffraction data.

The crystal structures of Hg4Sb2I3 and Cd4Sb2I3

Abstract The crystal structures of Hg 4 Sb 2 I 3 and Cd 4 Sb 2 I 3 have been solved by X-ray single crystal techniques. Hg 4 Sb 2 I 3 and Cd 4 Sb 2 I 3 are isostructural and crystallize in the cubic system, space group Pa 3, Z = 8, with cell dimensions a = 13.4392(6) A for Hg 4 Sb 2 I 3 and a = 13.4876(5) A for Cd 4 Sb 2 I 3 . The compounds have a three-dimensional array built from six-membered rings containing mercury (cadmium), antimony, and iodine atoms. One-half of the antimony atoms are bound into Sb 4− 2 pairs with an SbSb distance of 2.75 A. The absence of HgHg (or CdCd) and SbI bonding was determined.