Сжимаемость и электронные свойства цианидов металлов

The compressibility and electronic properties of metal cyanides are investigated within the density functional theory taking into account the dispersion van der Waals interaction. It was shown that gold cyanide has a low linear compressibility (less than 0.1% at a pressure of 1 GPa) and a high linear modulus (~ 1200 GPa) along the -Au-CN-Au-CN- chains. Silver cyanide exhibits negative linear compressibility, which correlates with the compressibility of Ag-N coordination bonds. For sodium cyanide, the linear compressibility along the C - N covalent bonds is greater than for gold and silver cyanides, while the elastic anisotropy is less. Unlike sodium cyanide, for gold and silver cyanides, cation-anionic bonds (Au-N, Au-C and Ag-N, Ag-C) are partially covalent in nature, and the upper valence states correspond mainly to the states of cations. The band gap of gold cyanide is smaller than that of silver and sodium cyanides. The band gap widths of gold and silver cyanides significantly decrease with increasing pressure, which indicates the possibility of metallization at sufficiently high pressures.

Role of the Outer Metal of Double Metal Cyanides on the Catalytic Efficiency in Styrene Oxidation

The catalytic efficiency of double metal cyanide (DMC) has been shown to be very effective in heterogeneous catalysis. The catalytic activity of the outer divalent cations (Mn, Co, Ni, and Cu) of a family of hexacyanocobaltates was examined in the oxidation reaction of styrene, as a model molecule, using tert Butyl Hydroperoxide (TBHP, Luperox®) as an oxidizing agent. The most electronegative outer cations showed the best conversions, with 95% for copper, followed by nickel with 85% conversion of the monomer at atmospheric pressure and temperature of 75 °C. The evidence showed that the catalytic activity and selectivity towards oxidized products are strongly linked to the accurate choice of the outer cation in the DMC together with the oxidizing agent.

Discovery of two new magnesium-bearing species in IRC+10216: MgC3N and MgC4H

We report on the detection of two series of harmonically related doublets in IRC +10216. From the observed frequencies, the rotational constant of the first series is B = 1380.888 MHz and that of the second series is B = 1381.512 MHz. The two series correspond to two species with a 2Σ electronic ground state. After considering all possible candidates, and based on quantum chemical calculations, the first series is assigned to MgC3N and the second to MgC4H. For the latter species, optical spectroscopy measurements support its identification. Unlike diatomic metal-containing molecules, the line profiles of the two new molecules indicate that they are formed in the outer layers of the envelope, as occurs for MgNC and other polyatomic metal-cyanides. We also confirm the detection of MgCCH that was previously reported from the observation of two doublets. The relative abundance of MgC3N with respect to MgNC is close to one while that of MgC4H relative to MgCCH is about ten. The synthesis of these magnesium cyanides and acetylides in IRC +10216 can be explained in terms of a two-step process initiated by the radiative association of Mg+ with large cyanopolyynes and polyynes followed by the dissociative recombination of the ionic complexes.

Neutralisation Process Design for Electroplating Industry Wastewater Containing Chromium and Cyanides

Manufacturing processes in the electroplating industry employ hazardous chemicals and generate hazardous waste, including hexavalent chromium compounds and heavy metal cyanides. We designed a reagent-based treatment technology that can remove these contaminants and is relatively simple to implement and maintain. The technology features low reagent consumption but high treatment efficiency and simplifies separating precipitates from the treated effluent. The paper presents a detailed description of how to neutralise electroplating shop wastewater. We propose a system of organizational and technological measures to improve chemical safety.