Structural characteristics of dicarbon polyfluoride

In chemical analysis and XRPA studies, it has been found that the products of fluorination of graphite, graphite bifluoride, and tetracarbon polyfluoride with gaseous and liquid fluorooxidants (ClF₃, ClF₅, XeF₂, and FNO₃) and their solutions in anhydrous hydrogen fluoride and freon-113 at 20–100°C, having a limiting composition, are second stage intercalated compounds based on dicarbon polyfluoride with the corresponding fluorooxidant, or the reduced form of fluorooxidant, or a fluorooxidant and a solvent. The degree of C-F bond ionicity in C₂F was higher than in CF, but lower than in C₄F. However, the bond is closer in character to the covalent C-F bond in monocarbon polyfluoride.     

Crystal structure of [Co(N2C2H8)3] [AuBr4]2Br bis(tetrabromoaurate(III))tris(ethylenediamine) cobalt(III) bromide

A double complex salt [Co(N₂C2H₈)₃][AuBr₄]₂Br is obtained and characterized using single crystal X-ray diffraction analysis. The crystallographic data of C₆H₂₄Au₂Br₉CoN₆ are as follows: a = 21.6479(17) ?, b = 14.9085(12) ?, c = 8.2676(7) ?, β = 110.820(2)°, V = 1538.92(12) ?³, C2/c space group, Z = 4, d _x = 3.602 g/cm³. Square planar coordination of the gold atom in the complex anion is completed to a tetragonal pyramid by an additional bromine atom of the adjacent complex anion at the Au... Br distance of 3.677 ?.     

Effect of fluorination on the surface properties of carbon materials as probed by gas chromatography

The surface properties of graphite, carbon fiber, and their fluorination products were studied using gas chromatography. The retention volumes and Kovatz indices for saturated and aromatic hydrocarbons and oxygenated and nitrogenated compounds were determined. Regardless of the properties of the matrix, fluorination produces materials with chemically homogeneous and apolar surfaces. For fluorinated graphite, the decrease in the retention of branched alcohols compared to that of linear alcohols is more significant than for fluorinated carbon fiber.     

The Hydrolysis of AuCl<Stack><Subscript>4</Subscript><Superscript>−</Superscript></Stack> and the Stability of Aquachlorohydroxocomplexes of Gold(III) in Aqueous Solution

The equilibria AuCl₄⁻+jOH⁻+kH₂O⇌AuCl_4−j−k (OH) _j (H₂O) _k ^k−1+(j+k)Cl⁻, β _jk (0≤j,k≤4) have been studied spectrophotometrically at 20 °C in aqueous solution. For I=2 mol⋅dm⁻³(HClO₄) the conventional constants, β _i ^*, of the equilibria, Au^*+iCl⁻ ⇌AuCl _i ^*, are equal to log ₁₀ β ₁^*=(6.98±0.08); log ₁₀ β ₂^*=(13.42±0.05); log ₁₀ β ₃^*=(19.19±0.09); and log ₁₀ β ₄^*=(24.49±0.07), where [AuCl _i ^*]=∑[AuCl _i (OH) _j (H₂O)_4−i−j ] at i=const. The hydrolysis and other transformations of AuCl₄⁻ in aqueous solution are discussed. On the basis of new and known data, a full set of equilibrium constants, β _jk , or their estimates has been obtained.     

Functional Composites Based on Polylactide and Graphene

New composite materials based on polylactide and graphene, suitable for creating three-dimensional objects using the 3D printing technology, were prepared. Introduction of the nanoadditive into the matrix of the biodegradable polymer enhances the tensile strength of the materials by more than 57%. In addition, the composites exhibit high electrical conductivity, reaching 0.9 S cm^–1 for the composite with 3 wt % filler, which determines the possibility of using them for the development of various electrotechnical devices and tissue engineering structures.     

Complex salts (DienH3)[IrCl6](NO3), (DienH3)[PtCl6](NO3), and (DienH3)[IrCl6]0.5[PtCl6]0.5(NO3): Synthesis, structure, and thermal properties

The complex salts ((DienH₃)[IrCl₆](NO₃) (I), (DienH₃)[PtCl₆](NO₃) (II), and (DienH₃)[IrCl₆]_0.5[PtCl₆]_0.5(NO₃) (III) (where Dien is NH₂(CH₂)₂NH(CH₂)₂NH₂) were synthesized and characterized by elemental, X-ray diffraction, and thermal analyses and by electronic and IR spectroscopies. Solid solution of the composition Ir_0.35Pt_0.65 was obtained by decomposition of compound III in the atmosphere of hydrogen. Original Russian Text ? E.V. Makotchenko, I.A. Baidina, P.E. Plusnin, L.A. Sheludyakova, Yu.V. Shubin, S.V. Korenev, 2007, published in Koordinatsionnaya Khimiya, 2007, Vol. 33, No. 1, pp. 47–54.     

Small-angle neutron scattering from samples of expanded carbon

The subatomic structure of expanded graphite has been investigated by small-angle neutron scattering. Samples were synthesized during quick thermal decomposition of intercalated compounds based on oxidized graphite. They had a low bulk density (up to 0.1 g/cm³) and were characterized by considerable small-angle scattering. It has been established that majority of the volume of expanded graphite samples is occupied by participles with characteristic sizes in two ranges: from 6 to 8 nm and from 20 to 30 nm. Small particles have properties of a surface fractal with the dimension D _s = 2.4–2.6, whereas the larger particles are mainly smooth and have the dimension D _s = 2.0–2.1. The specific surface of the samples studied was determined from the small-angle scattering data.     

Superfine Expanded Graphite with Large Capacity for Lithium Storage

A superfine expanded graphite (s‐EG) fiber material was investigated as an anode material for lithium‐based batteries. The fibers were prepared by decomposition of dicarbon monofluoride‐intercalated graphite. The high resolution transmission electron microscopy (HRTEM) images showed the fiber thickness in range of 2–3 nm with several microns in length. Lithium storage capacity in this material was measured in lithium half cells. High lithium storage capacity of about 1000 mAh · g^–1 at a rate of C/10, corresponding to Li₃C₆ composition was obtained. The material showed fairly good rate capability exhibiting lithium storage capabilities even at 60C. As a effect of ball milling, the s‐EG showed crystallographic ordering in the sample with reduced the lithium storage capacity corresponding to composition of LiC₆. A simple mathematical relation to account for the excess lithium storage capacity in this material is put forward.     

Structural investigation of [Au(en)<Subscript>2</Subscript>]Cl(ReO<Subscript>4</Subscript>)<Subscript>2</Subscript> and [Au(en)<Subscript>2</Subscript>](ReO<Subscript>4</Subscript>)<Subscript>3</Subscript> complexes

Novel complex salts [Au(en)₂]Cl(ReO₄)₂ (I) and [Au(en)₂](ReO₄)₃ (II), en = ethylenediamine, are obtained. Their crystal structures are determined by single crystal X-ray diffraction. Complex I crystallizes in the triclinic crystal system: a = 6.2172(7) Å, b = 7.1644(8) Å, c = 8.8829(8) Å, α = 96.605(4)°, β = 110.000(4)°, γ = 97.802(4)°, P-1 space group, Z = 1, d _x = 3.905 g/cm³; complex II crystallizes in the monoclinic crystal system: a = 15.244(2) Å, b = 7.6809(8) Å, c = 9.3476(12) Å, β = 127.004(3)°, C2 space group, Z = 4, d _x = 4.057 g/cm³.