Nitric oxide decomposition over BaRuxBi1?xO3 (X=0.33, 0.50, 0.67, 1.00) perovskite-like catalysts

The catalytic activity of Ba₂Ru_0.67Bi_1.33O₆, Ba₂RuBiO₆, Ba₃Ru₂BiO₉ and BaRuO₃ towards NO-decomposition prior to and after treatment with NH₃ has been studied. About 100% degree of conversion has been achieved at 400°C for samples with the highest percentage of hexagonal stacking in their crystal structures. It has been shown that the active sites are units of two or three face-sharing [RuO₆] octahedra in which a strong Ru−Ru interaction takes placevia the common faces.     

A New catalytic reaction for determination of nanogram amounts of copper

Summary A simple and very sensitive new catalytic method is proposed for determination of copper(II). The method is based on the oxidation of sulphanilic acid with H₂O₂ at pH 7 in the presence of pyridine as activator. The sensitivity of the method is 5 ng/ml. Cobalt(II) interferes at concentrations of the same order as copper(II). The method is suitable for determination of copper in biological materials.

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Zusammenfassung Eine einfache und sehr empfindliche katalytische Methode zur Bestimmung von Kupfer(II) wurde vorgeschlagen. Sie beruht auf der Oxydation von Sulfanilsäure mit Wasserstoffperoxid bei pH 7 in Gegenwart von Pyridin als Aktivator. Ihre Empfindlichkeit beträgt 5 ng/ml. Kobalt(II) stört in Konzentrationen der gleichen Größenordnung wie Kupfer(II). Das Verfahren eignet sich zur Kupferbestimmung in biologischem Material.

     

Catalytic reactions-I Mechanisms

The mechanisms of some reactions used in catalytic analysis are discussed. The knowledge of the mechanism of a catalytic reaction can help in the development of new catalytic reactions and the choice of optimal conditions, and to show the possibilities for further increases in sensitivity.     

Linear-dichroic infrared spectral analysis of Cu(I)-homocysteine complex

The interaction between homocysteine (HCysSH) and Cu(II) leads to the formation of a yellow complex [Cu(I)(HCysS-SCysH)2]Cl (1) after redox processes in the Cu(II)-homocysteine system resulting in dimerization of the ligand and formation of a mononuclear Cu(I) complex with two dimers. The structure of (1) was obtained by IR-LD spectral analysis of a solid amorphous sample oriented in nematic liquid crystal medium. The original technique for orientation developed here and the polarized IR spectra thus obtained, permit the determination of the complexation sites and coordination mode of diamagnetic complexes. In the complex (1), Cu(I) is coordinated through the two O atoms of one COO- group of each of the ligands and the metal ion coordination sphere represents a distorted tetrahedron.     

A four-membered chelate complex of Cu(II) with creatinine

The complex formation between Cu(II) and creatinine was studied by means of electronic, IR and EPR spectroscopy. The spectral data show the formation of a Cu(II) four-membered chelate with distorted rhombic structure.     

Application of decarboxylation reactions in catalytic analysis determination of aluminium

Summary The activation of the catalytic decarboxylation of oxaloacetic acid with some pyridine derivatives was studied in order to select suitable activators for increasing the sensitivity of this type of analytical catalytic reactions. The catalytic activity of some bivalent metal ions (Cu²⁺, Zn^2s+, Cd²⁺, Pb²⁺) as well as that of Al³⁺ was also studied. On that ground a catalytic method for determination of aluminium was developed. The sensitivity of the method is 0.5g of aluminium in the sample.

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Zusammenfassung Die Aktivierung der katalytischen Decarboxylierung von Oxalessigsäure durch einige Pyridinderivate wurde untersucht, um geeignete Aktivatoren zur Steigerung der Empfindlichkeit dieser analytisch auswertbaren Reaktion zu finden. Die katalytische Aktivität einiger zweiwertiger Metallionen (Cu, Zn, Cd, Pb) sowie von Al wurde ebenfalls geprüft. Auf dieser Grundlage wurde eine Methode zur Aluminiumbestimmung entwickelt, deren Empfindlichkeit zur Bestimmung von 0,5g Al je Einwaage ausreicht.

     

Copper-linked hexaniobate lindqvist clusters-variations on a theme

Four new one-dimensional materials and one dimer complex based on the linkage of [Nb6O19] clusters and [CuLx] (L=ethylenediamine (en), NH3, H2O) assemble under ambient conditions. These phases include the following: Rb4[Cu(en)2(H2O)2]3[(Nb6O19H2)2Cu(en)2].24H2O (1), space group P; [Cu(en)2(H2O)2]2[(Nb6O19H2)Cu(en)2].14H2O (2), space group P; Rb2[Cu(NH3)2(H2O)4][Cu(NH3)4(H2O)2]2{[Nb6O19][Cu(NH3)]2}(2).6H2O (3), space group P; {[Nb6O19][Cu(NH3)2(H2O)]2[Cu(H2O)4]2}.3H2O (4), space group P2/n; and {[Nb6O19][Cu(NH3)2(H2O)]2[Cu(H2O)4]2} (5), space group C2/m. All structures have been solved by single-crystal methods, and compounds 1-5 were characterized by thermogravimetric analysis, Fourier transform IR, chemical analysis, and magnetic measurements. It has been demonstrated that the conformation, charge, and geometry of the [Nb6O19]-[CuLx] chains can be modulated by varying the type and amount of the [CuLx]2+ species. The charge balance is provided by mixed Rb+/[CuLx]2+ or [CuLx]2+ cations only for structures 1-3, whereas 4 and 5 are neutral chains with no counterions. There are weak antiferromagnetic Cu2+-Cu2+ interactions in all phases. Compounds 2-5 represent the first examples in which the [Nb6O19] Lindqvist ion forms extended solids rather than dimers or decorated monomers when reacted with transition-metal, cationic complexes.