Formation of various polymeric frameworks by dicarboxylate-like ligands: Synthesis and crystal structures of polymeric complexes of sodium perchlorate with flexible double betaines

Three crystalline complexes of sodium perchlorate with different flexible double betaines [Na ₂(L¹)(ClO₄)(H₂O) _n ](ClO₄) _n (1), [Na ₃(L²)(ClO₄)₃(H₂O)_{2 n} ] (2), and [Na(L ³)(CH₃OH)_n]-(ClO₄) _n ·xnH₂O (x=0.25) (3) [^–O₂CCH₂N⁺Me₂–(CH₂) _n -N⁺Me₂CH₂CO₂ ^–,n=2 L¹;n=3 L²;n=4 L³] have been synthesized and characterized by single-crystal X-ray structure analysis. Complex (1) comprises tetranuclear sodium units consolidated by betaine and aqua ligands, which are bridged by half of the ClO₄ ^– anions to form layers matching the (200) planes, the remaining uncoordinated ClO₄ ^– anions being accommodated between adjacent layers. Complex (2) possesses a double-layer polymeric structure with the sodium atoms bridged by ligand oxygen atoms to form columns running parallel to thea axis, which are interconnected by double-betaine ligands lying parallel to theac plane. All of the ClO₄ ^– groups and water molecules are coordinated to the metal atoms. In complex (3) the chains composed of alternating eight-membered and four-membered metallocycles are cross-linked by the betaine ligands, which lie in the (020) and (01/1) families of planes, to yield a three-dimensional network. All of the ClO₄ ^– groups and water molcules fill the resulting infinite channels running parallel to thea axis. Two unusual carboxylate coordination modes are identified, namely ₃-O andhapto-3-O plushapto-2-O in (1) and (2), respectively.     

Solvent-Free Thiolysis of Epoxides under Lithium Perchlorate Catalysis

Summary. Solvent-free ring opening of 1,2-epoxides with thiols using catalytic amounts of lithium perchlorate affords high yields of β-hydroxy sulfides. Nucleophilic attack of the thiols occurs regioselectively at the sterically less hindered side of the epoxides.     

Reactions of oxonium derivatives of [B12H12] with amines: Synthesis and structure of novel B12-based ammonium salts and amino acids

The reactions of oxonium derivatives of [B₁₂H₁₂]²⁻ with various amines were studied. A series of novel B₁₂-species with ammonium group on the side chain was synthesized in high yield. A structure of tetrabutylammonium-[2-(2-morpholinium-ethoxy)-ethoxy]-undecahydro-closo-dodecaborate was determined and the existence of intramolecular N-H?O-B bond was shown. Using these reactions, novel boronated piperazines and amino acids were prepared.     

Lanthanide perchlorate complexes of 2-acetamidopyridine-1-oxide

2-acetamidopyridine-1-oxide (AcAmPyO) complexes of six lanthanide perchlorates, with the general composition Ln(AcAmPyO)₅ (ClO₄)₃, have been synthesized and characterized by analysis, molar conductance, infrared, proton NMR and electronic spectral data. Infrared and conductance studies indicate the ionic nature of the anion. The coordination of the ligand through the N-O and C=O moieties is shown by the infrared and proton NMR spectral analysis.     

HPLC of aminoacids on silica coated with ammonium tungstophosphate

Summary The chromatographic behaviour of aminoacids on columns of silica coated with different percentages of ammonium tungstophosphate at several buffer phosphate concentrations is reported. The stationary phase shows a high selectivity towards aminobutyric acids and methyl derivatives of tryptophan due to the distance between the carboxylic group and the –NH ₃ ⁺ group involved in the cation-exchange process and/or to the steric hindrance by a methyl substituent. A relationship between HPLC and HPTLC data has been verified and applied to the prediction of the separation of six aminoacids.     

亚硫酸根离子在硅和二氧化硅的湿法腐蚀中的作用

运用光刻技术和原子力显微技术(AFM)研究了亚硫酸根离子对硅和二氧化硅在40％(w)氟化铵水溶液中腐蚀速率的影响.结果表明硅和二氧化硅的腐蚀速率和亚硫酸根离子浓度有关.高分辨X射线光电子能谱(XPS)分析在有/没有亚硫酸根的溶液中腐蚀后的硅和二氧化硅表面氟元素的结果表明在这两种溶液中腐蚀得到的表面化学成分是有差别的.实验结果证明亚硫酸根离子在硅和二氧化硅的湿腐蚀中不只是表现为一种除氧剂，还干预了表面腐蚀反应过程.     

FTIR study of ion dissociation in PMMA based gel electrolytes containing ammonium triflate: Role of dielectric constant of solvent

The effect of dielectric constant of solvent on the presence of ion aggregates/undissociated salt and their dissociation with the addition of polymer has been studied by FTIR for polymethylmethacrylate (PMMA) based gel electrolytes containing ammonium triflate (NH₄CF₃SO₃). Salt is fully dissociated in electrolytes containing dimethylacetamide (DMA)—a high dielectric constant solvent and some ion aggregates are also present whereas in electrolytes containing diethylcarbonate (DEC)—a low dielectric constant solvent, some undissociated salt is present. The conductivity behaviour of polymer gel electrolytes has been found to depend upon the dielectric constant of the solvent used. PMMA plays the role of a stiffener in electrolytes containing DMA and results in a small decrease in conductivity whereas in electrolytes containing DEC, the addition of PMMA results in an increase in conductivity which has been explained to be due to an increase in free ion concentration by the dissociation of undissociated salt and ion aggregates. The presence of free ions, ion aggregates, undissociated salt has also been examined by FTIR spectroscopy.     

A re-interpretation of the crystal structure of ‘(NH4)2(NH3)[Ni(NH3)2Cl4]’ in terms of (NH4)2−2z[Ni(NH3)2]z[Ni(NH3)2Cl4]

A re-interpretation and re-evaluation of single-crystal X-ray diffraction data of a previously reported ‘(NH₄)₂(NH₃)[Ni(NH₃)₂Cl₄]’ (J. Solid State Chem. 162 (2001) 254) give a new formula (NH₄)_2−2z[Ni(NH₃)₂]_z[Ni(NH₃)₂Cl₄] with z=0.152. This new formula results from defects in an idealized ‘(NH₄)₂[Ni(NH₃)₂Cl₄]’ basic structure, where two adjacent NH₄⁺ cations are replaced by one Ni(NH₃)₂²⁺ unit. Cl⁻ anions from the basic structure complete the coordination sphere of the new Ni²⁺ to [Ni(NH₃)₂Cl₄]²⁻.     

Lithium perchlorate suspend in methylene chloride, a mild, efficient and reusable catalyst for the synthesis of ferrocene aminonitrile derivatives

A practical and efficient method for the synthesis of α-aminonitriles of ferrocene by one-pot three-component reaction of ferrocenecarboxaldehyde, trimethylsilyl cyanide and amines catalyzed by lithium perchlorate suspend in CH₂Cl₂ is reported under mild and neutral reaction conditions in high yields and short reactions times.     

Intradiffusion coefficients for perchlorate ions in zinc perchlorate and zinc chloride solutions at 25°C: Comparing transport properties of zinc chloride and zinc perchlorate systems

Intradiffusion coefficients for³⁶ClO ₄ ^– have been measured in solutions of zinc perchlorate of concentration 0.1 to 3 mol dm^–3 at 25°C by the diaphragm cell technique. In addition, intradiffusion coefficients for perchlorate ions in zinc chloride solutions have been measured over a concentration range at 25°C. The results confirm previous work on the effect of complexation on diffusion in zinc chloride solutions above a salt concentration of 0.1M. The present data, together with literature data for diffusion coefficients of the other species present in the zinc perchlorate electrolyte system, have enabled a simple analysis of the hydration around the zinc ions to be carried out. This indicates that the water diffusion data are consistent with the zinc ions having an effective hydration sphere of 11 (±2) water molecules. This is in keeping with values obtained for other simple divalent electrolytes using the same model. The model is extended here to allow analysis of water diffusion in zinc chloride solutions taking into account the presence of complexed chloro-zinc species. The experimental data are consistent with the effective hydration of the chloro-zinc complexes being independent of the number of chloride ligands and equal to 18±3 over a concentration range of 0 tol mol-dm^–3. This postulate is discussed in terms of its consequences on the water ligand dynamics for the complex equilibria.