Studies of the electrodeposition of palladium from baths based on [Pd(NH3)2X2] salts. I. [Pd(NH3)2Cl2] baths

Spectroscopic techniques are used to confirm the chemistry of solutions of [Pd(NH₃)₂Cl₂] in aqueous NH₄Cl at various pH. In addition, potential sweep and step methods at rotating and stationary disc electrodes (both vitreous carbon and freshly plated palladium) are used to investigate palladium deposition from a standard electroplating bath, [Pd(NH₃)₂Cl₂] in NH₄Cl/NH₃ (pH 8.9). The relative importance of oxygen reduction, hydrogen absorption and hydrogen evolution as competing cathode reactions under various conditions is defined and the advantage of strong convection for high rate plating is demonstrated.     

Studies of platinum electroplating baths: Part V: Solutions derived from Pt(NO2)42? in aqueous acid

When Pt(NO2)42– is dissolved in methanesulphonic acid, it is shown that nitrite ions are displaced by water ligands and the extent of ligand substitution depends on temperature, length of the thermal treatment and the concentration of acid. Although the final nitrite ligand is difficult to displace, a solution containing Pt(NO2)(H2O)3+ as the dominant species may be formed, and this solution (Pt concentration 6gdm–3) provides the basis of a reasonable Pt plating bath. At a temperature of 343K, good quality coatings can be obtained with current densities in the range 1–15mAcm–2 although the current efficiencies are low (10–15%) because reduction of the nitrite ion competes with Pt deposition on the freshly formed Pt surface.     

Synthesis and crystal structure of mer-nitroaquatriamminenitrosylruthenium(II) nitrate [RuNO(NH3)3(NO2)(H2O)](NO3)2

The reaction between mer-[RuNO(NH₃)₃(NO₂)(OH)]Cl·0.5H₂O and an excess of 16 M HNO₃ leads to the protonation of the starting complex and crystallization of the complex with a coordinated water molecule and nitrite anion. The crystal structure of the product has been determined. The coordinated water molecule tends to be a weak acid with a measured pK_a of 2.4.     

无铅或少铅钙钛矿CH3NH3M1-xPbxX3(M=Sn,Sr;X=Cl,Br,I)太阳能电池的研究进展

本文综述了Sn2+或Sr2+取代的无铅或少铅钙钛矿CH3NH3PbX3 (X=Cl,Br,I)的结构及其主要的制备方法,评述了各种方法的优缺点.简要介绍了无铅或少铅钙钛矿材料的能隙以及材料的稳定性对太阳能电池的影响,并对其发展前景进行了展望.     

Mesogenic Pd(II) complexes based on 3-substituted pyrazol ligands

A new family of linear Pd(II) complexes based on pyrazoles containing long-chain substituents at the third position has been prepared and their mesomorphic properties studied. The crystalline structure of one of these compounds is described as a representative example of a very elongated and straight molecule.     

Well defined CuI(NO), CuI(NO)2 and CuII(NO)X (X = O− and/or NO 2 − ) complexes in CuI-ZSMS prepared by interaction of H-ZSM5 with gaseous CuCl

In this note an exchange procedure of the acidic protons of H-ZSM5 by Cu^I ions through reaction with CuCl in the gas phase is described. In the so obtained Cu^I-ZSM5 exchanged zeolite the Cu^I ions are in well defined configuration and form with NO mono and di-nitrosyl complexes of high structural and spectroscopic quality. The Cu^I(NO)₂ species are transformed at RT into Cu^II(NO)X (X=O^– and/or NO ₂ ^– ) species which could represent an intermediate in NO decomposition.     

The metal-chain complexes (X)[Os(CO)3(CNBut)]3Mn(CO)5 (X=Cl,Br, I)

In what is a new metal-chain forming reaction, (X)[Os(CO)₃(CNBu^t)]₃Mn(CO)₅ (X=Cl, Br, I) complexes have been prepared by the successive addition of Os(CO)₄(CNBu^t) to Mn(CO)₅(X) in hexane. The crystal structure of the iodo derivative reveals it to contain an approximately linear Os₃ Mn chain of metal atoms.     

Ferroelectric and ferroelastic phase transitions in (CH3NH3)3Sb2Br9 crystals

(CH₃NH₃)₃Sb₂Br₉ crystals were studied by pyroelectric method in the temperature range 10 - 200 K. Pyroelectric measurements revealed reversal spontaneous polarization below 141 K along the a-axis. The optical observations showed that MABA possesses ferroelastic domains in all low temperature phases.     

Studies of platinum electroplating baths Part IV: Deposits on copper from Q bath

The deposition of platinum on copper from a modern commercial electroplating bath (Pt 5Q bath containing 26mm Pt(NH₃)₄HPO₄ 30 mm sodium phosphate buffer, pH 10.6 at 368 K) has been studied using voltammetry and potential step methods. In addition, polished Cu panels (area 3.4 cm²) have been electroplated using both constant potential and constant current conditions; current efficiencies have been determined and scanning electron microscopy has been used to show that the morphology of the platinum layers depends strongly on the plating conditions, particularly the potential at which deposition occurs. It is shown that good quality electroplates can be obtained with high current efficiency but a high rate deposition is more readily achieved using controlled potential.     

Quasi-Classical Trajectory Studies of H + HX → H2 + X (X = Cl,Br, I) Reaction at High Collision Energy

Quasi-classical trajectory calculations have been performed to investigate the dynamics of the H + HX → H₂ + X reactions, where X = Cl, Br, and I. Calculations were performed for two collision energies, 16 and 36 kcal mol⁻¹. The results show that the dynamics of the abstraction reactions at these high collision energies are rather unusual. The product energy and angular distributions can be accounted for by a mechanism that involves an isolated interaction between the two H atoms in the system to form H₂ followed by hard-sphere scattering of this newly formed H₂ off the X atom.     

The phenomenon of conglomerate crystallization. Part 56. The crystallization behavior of [(tren)Co(N3)2]X (X = Br,I): centrosymmetric to Sohnke space group phase transition caused by cooling

[(tren)Co(N₃)₂]Br (I) and [(tren)Co(N₃)₂]I (III) was prepared and its crystal structure determined at 293 and at 120 K. At room temperature (293 K), (I) crystallizes as a conglomerate in space group P2₁2₁2₁ and remains so at 120 K, (data sets Ia and Ib, respectively). The iodide crystallizes as a racemate, space group P2₁/n (z=4), data set (IIIa); but, cooling to 120 K results in a phase change whereby the crystal is enantiomorphic (IIIb) + (IIIc), space group P2₁(z=4). There is no damage to the crystal upon undergoing the phase transition (IIIa) → (IIIb) + (IIIc). In fact, the same crystals were used to collect the data sets which were cycled as follows: 293 → 120 → 293 K. The two molecules in the asymmetric unit of (IIIb and IIIc) are homochiral demanding that the phase transition observed causes the inversion of the axial chirality of one of the five-membered rings of the iodide. This result is reproducible and was observed for all crystals cooled to 120 K. Differential scanning calorimetry confirms the existence of phase changes in the crystalline material as a result of cooling.     

Selective catalytic reduction of NO by NH3 on Cu (II) ion-exchanged offretite prepared by different methods

The influence of the preparation method on the NO–SCR by NH₃ activity of Cu-OFF catalysts has been studied on presence of oxygen. The catalysts structure and the nature of copper species have been investigated by XRD, ²⁷Al MAS NMR, UV-visible spectroscopy and H₂-TPR. Among the examined preparation methods, the ionic exchange in aqueous solution gives the highest efficient catalyst in NO-SCR. It is shown that Cu cationic species are formed in large extent with this method despite the presence of minor amounts of small oxide clusters.     

A promising optical limiting material: Tunable third-order nonlinear optical properties of robust CsPbX3 (X=Cl/Br,Br) nanocrystals glasses

As laser technology advances, the importance of laser protection puts an urgent demand for robust and high-efficient optical limiting materials. In this work, CsPbX₃ (X = Cl/Br, Br) NCs were synthesized by precisely controlling the ratio of Cl⁻ to Br⁻ and the heat treatment temperature, and the third-order nonlinear (TONL) optical properties of them were investigated systematically and deeply based on a nonlinear optical imaging technique with the phase-object (NIT-PO) at 532 nm for the first time. All of them demonstrate strong reverse saturation absorption (∼10^-12–10^-11 m/W), and the sign of TONL refraction index (γ) relates to the component (CsPb(Cl/Br)₃ NCs glasses: ∼10^-20 m²/W, CsPbBr₃ NCs glasses: ∼−10^-20 to 10^-19 m²/W). In addition, they have excellent characteristics of thermal stability and water stability, as well as photostability under 455 nm laser irradiation, indicating that it is a promising optical limiting material.     

Phase transitions in R2 SnCl6-type crystals (R = NH3 C2H3, NH3C2H5 and N(CH3)4)

The thermal dilatation in (NH₃ ·CH₃) SnCl₆, (NH₃ · C₂H₅) SnCl₆ and [N(CH₃)] SnCl₆ was measured, and as the results it has turned out that (NH₃ ⁶·C₂H₅) SnCl₆ and [N(CH₃)₄]₂ SnCl₆ undergo the first order transitions at 128 K and 158 K, respectively. The low temperature phases of (NH · C₂H₅) SnCl₆ and [N(CH₃)₄]₂ SnC1₆ are found to be monoclinic and tetragonal, respectively, No phase transition was observed in (NH₃ ·CH₃)₂ SnCl₆ down to 77 K.     

Cathodic electrodeposition of Y(OH)3 and Y2O3 nanostructures from chloride bath. Part II: Effect of the bath temperature on the crystal structure,composition and morphology

Ultra-fine nanoparticles, mono-dispersed nanospheres and nanorods of Y(OH)₃ and Y₂O₃ were successfully prepared via electrodeposition from chloride bath at different temperatures of 10, 25, 40 and 80 °C followed by heat-treatments at 600 °C in dry air atmosphere. Thermal behavior of the hydroxide samples was investigated by differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis. The structural and morphological characteristics of the products were determined by X-ray diffraction (XRD), FT-IR, scanning and transmission electron microscopy (SEM and TEM). Effects of bath temperature on the mechanism of base electrogeneration and deposit formation on the cathode surface were proposed and discussed. The results showed that the crystal structure, composition and morphology of the products are mainly affected by the temperature of electrodeposition bath.     

Facile synthesis of new Pd(II) and Cu(II) based metallomesogens from ligands containing thiophene rings

Very simple synthetic procedures, involving use of tin/amine complex afford two new mesogenic thiophene derivatives. These can chelate palladium(II) or copper(II) producing the corresponding metallomesogens. The liquid crystal properties of all compounds were investigated by calorimetry, polarizing microscopy and X-ray diffraction techniques. Molecular and crystal structure of one ligand and two complexes were analyzed by single crystal X-ray diffraction. Connections between structural features and phase behaviour are discussed.     

NO与Co(NH3)2+6气液反应动力学

用Co(NH₃)²⁺₆的氨水溶液可同时实现NO的氧化和吸收过程.NO 与Co(NH₃)²⁺₆气液反应动力学研究表明,NO与Co(NH₃)²⁺₆的反应为瞬间反应,当Co(NH₃)²⁺₆浓度低于20mmol•L^-1时过程为双膜控制,当Co(NH₃)²⁺₆浓度大于20mmol•L^-1时过程逐渐变为气膜控制.NO的吸收速度随温度的升高而降低,气相中氧的存在有利于NO的吸收,但当氧的含量高于5.2%后再继续增加氧的含量NO吸收速率提高不大.经研究建立了有氧时NO 与Co(NH₃)²⁺₆气液反应动力学方程.     

Solubility in system CO(NH2)2-NH4NO3-H3PO4-H2O

Solubility data were obtained in the system CO(NH₂)₂-NH₄NO₃-H₃PO₄-H₂O at 0° and 15°C. The results show that high-analysis solution fertilizers can be produced from standard urea-ammonium nitrate (UAN) and phosphoric acid materials. These acidic solution fertilizers contain up to 35% total plant nutrient (TPN = N + P₂O₅ + K₂O), with N:P₂O₅ ratios varying from 20:1 to 1.5:1. Potential liquid products having fertilizer grades of 23-12-0, 26-9-0, 28-6-0, and 31-3-0 are feasible.     

Studies on the hydrogenation of olefins using polymer-bound palladium (II) species

bis-Benzonitriledichloropalladium(II) [(PhCN)₂PdCl₂] has been supported on two copolymers containing carboxyl and pyridyl groups and has been employed as a catalyst for the hydrogenation of olefins under mild conditions. The coordination environment and the nature of the metal species on the polymer have been studied by IR, ESCA, X-ray and a chemical test based on KCN treatment. Based on experimental evidence it is proposed that the polymer-palladium complexes initially contain palladium atoms with chlorine atom bridges which are cleaved in the activation. The catalysts were found to be active towards the hydrogenation of olefins under ambient conditions (room temperature and 1 atmosphere total pressure). The kinetic and mechanistic aspects of the hydrogenation of styrene and acrylonitrile and recycling capacity data using one catalyst (Cat-I) are reported.