Metallionen und H2O2. VI. Über Struktur und Aktivität der den H2O2-Zerfall katalysierenden Ni2+-Komplexe

The catalytic properties in H₂O₂ decomposition of Ni²⁺-chelates of the following ligands have been investigated: ethylenediamine, diethylenetriamine, triethylenetetramine, 2,2′-bipyridine, pyrophosphate and ethylenediamine-N, N, N′, N′-tetra-acetic acid, and of the following peptides and peptide-like ligands: glycylglycine, N,N′-diglycyl-ethylenediamine, N, N′-diglycyl-1, 5-diaminopentane and polymyxin B.     

über Struktur und Aktivität der den H2O2-Zerfall katalysierenden Cu2+-Komplexe VII

It has been stated in a preceding paper [3] that only parts of a ligand coordinated to a metal ion can be oxidized by H₂O₂ (= peroxidative activity). Considering the reversal of this statement to be true, it is shown by means of the peroxidative activity of the Cu²⁺-complexes of ATP, ITP, CTP, UTP, and TTP that in these complexes the heteroaromatic groups contribute to the coordination of Cu²⁺ ion. By analogy with the Cu²⁺-ATP-complex, where a macrocyclic phosphate-metal-adenine chelate is formed [4], and based on his experimental results, the author considers the existence of such a macrocyclic chelate in the copper complexes of ITP, GTP, CTP, UTP, and TTP as established. The coordination sites of the heteroaromatic groups in these complexes are discussed.     

Metallionen und H2O2. V. Über Struktur und Aktivität der den H2O2-Zerfall katalysierenden Cu2+-Komplexe III. Versuche zur Lösung von Strukturproblemen mit Hilfe der Katalyseeigenschaften

The catalytic properties of Cu²⁺-chelates of the following ligands in H₂O₂ decomposition have been investigated: N, N′-diglycyldiaminoethane (I), N, N′-diglycyl-1,5-diaminopentane (II), N, N′-diglycyl-1,3-diaminopropane (III) [6], glycinamide (IV), glycylglycinamide (V) and polymyxin B (VI). It is confirmed that the catalysis of H₂O₂ decomposition by Cu²⁺-chelates and the formation of ternary peroxo complexes (absorbing at 360 nm) depend on the number of free coordination positions. It is now shown that in reversal the number of free coordination positions on the Cu²⁺ in its complexes can be determined by measuring their catalytic activity on the H₂O₂ decomposition, and their absorption at 360 nm.     

Über Struktur und Aktivität der den H2O2-Zerfall katalysierenden Cu2+-Komplexe. V. Vergleich der katalytischen Aktivität der Cu2+-Komplexe isomerer β-Hydroxythiophen-Derivate. Mettallionen und H2O2, 9. Mitteilung

The catalytic properties in H₂O₂ decomposition of the Cu²⁺-chelates of 2- Acetyl-3-hydroxy-thiophene (I) and 3-Acetyl-4-hydroxy-thiophene (II) have been investigated. Evidence is given that the catalytic activity of the chelates is a function of the respective bond orders of the α, β (I) and β, β′ (II) thiophene bonds of the chelate ring.     

Über den Einfluss nichtpolarer Lösungsmittel auf Lage und Intensität von Absorptionsbanden in den Elektronenspektren apolarer Molekeln: II. Polyacetylene

The dispersive interaction of nonpolar solutes with nonpolar solvents is investigated in model systems consisting of solutions of dimethyl-tetraacetylene, di-t-butyl-tetraacetylene, dimethyl-pentaacetylene or di-t-butyl-pentaacetylene in binary mixtures of cyclohexane/carbondisulfide or n-pentan/carbondisulfide. For this purpose the ¹Σ → ¹Σ transition in the electronic spectrum of the solutions has been recorded. With increasing concentration of the more strongly interacting solvent component (i.e. carbondisulfide) bathochromic shifts δν of the transition frequency accompanied by a decrease in oscillator strength f_M are observed, which are consistent with calculated values based on a previously proposed exciton model [1].     

Über Chalkogenolate. 109. Untersuchungen über Perthiocyansäure 2. Darstellung und Eigenschaften der freien Säure

On Chalcogenolates. 109. Studies on Perthiocyanic Acid. 2. Preparation and Properties of the Free Acid Pale yellow perthiocyanic acid has been prepared by reaction of an aqueous solution of barium perthiocyanate with dilute hydrochloric acid at 0°C in the presence of diethyl ether. The infrared, electron absorption, and mass spectra are communicated.     

Übergangsmetallchalkogenverbindungen. Über CuNH4WS4 und Cu2WS4 und andere Übergangsmetallchalkogenmetallate

Transition metal chalkogen compounds. On CuNH₄WS₄, Cu₂WS₄ and other transition metal chalkogenometallates The preparation, vibrational and electronic spectra of CuNH₄WS₄, Cu₂WS₄ and other transition metal compounds, which could not be isolated in a pure form, are reported. The X-ray data of CuNH₄WS₄ are given.     

Über die Elektronenspinresonanzspektren einiger Cu2+-Komplexe in wässeriger Lösung

The e.s.r. spectra of aqueous solutions of Cu²⁺-complexes with a series of methylpyridines (PYR) have been investigated at liquid nitrogen temperature. The experimental data indicate that the formula CU(PYR) holds for the compounds in the frozen solutions. The marked decrease of the copper hyperfine coupling constant for some of the complexes is explained in terms of a distortion of the square planar structure towards a tetrahedral environment of the Cu²⁺. An analogous interpretation of the e.s.r. spectra of some copper containing electron-transfer-oxidases, e.g. ceruloplasmin and laccase, presents a possible explanation of the experimentally observed connections between the spectra and the enzymatic activity of these compounds.     

Über die acetolysenprodukte der cyanhydrine von 4-pyridazoin und 4-pyridoin: Struktur und ungewöhnliche reaktivität 9. Mitteilung über pyridazine

4-Pyridazoinecyanohydrin was found to be converted into the 1,4-dihydropyridazine derivative 2a on treatment with acetic anhydride. Structures of 2a and the corresponding 4-pyridine derivative 2b were assigned on the basis of spectroscopic data. Chromatography of 2a on silica gel using methanol as eluent yielded methyl 4-pyridazinecarboxylate. The pyridine derivative 2b under similar conditions was converted into a mixture of methyl isonicotinate and 4-pyridinylmethyl acetate. Mechanisms of these unexpected reactions are discussed.     

Über den Einfluss nichtpolarer Lösungsmittel auf Lage und Intensität von Absorptionsbanden in den Elektronenspektren apolarer Molekeln: I. Modell

Based on the assumption that the influence of the solvent on the wavelength and intensity of the absorption spectrum of non-polar molecules is due to Coulombic interaction of the electronic transition moments, three models are presented to calculate the wavelength and intensity changes using perturbation theory. In addition a computer program which allows to calculate solvent effects by simulation of the molecular solvent shell is developped. Using known data from solution spectra of polyenes, the experimental wavelength and intensity changes are compared with the calculated values.     

Zur Kinetik des durch Cu2+-Äthylendiamin katalysierten H2O2-Zerfalls: Metallionen und H2O2, 14. Mitteilung

Kinetic studies of the Cu²⁺-ethylenediamine catalysed decomposition of H₂O₂ show the initial rate v₀ of H₂O₂ decomposition to be proportional to [H+]^?1, [H₂O₂], and [Cu²⁺-en]². Maximal velocity is found at a ratio of [Cu²⁺]_tot:[en]_tot = 1:1,5. It is suggested that the active complex has a binuclear structure. This structure and probable mechanisms of the reaction are discussed. The kinetic measurements of the Cu²⁺-diethylenetriamine-H₂O₂ system are difficult to interprete because of degradation of the ligand by H₂O₂.     

Über Chalkogenolate. 89. Untersuchungen über N-Dicyandithiocarbamidsäure Darstellung und Eigenschaften der freien Säure

On Chalcogenolates. 89. Studies on N-Dicyandithiocarbamic Acid. Preparation and Properties of the Free Acid Colorless N-dicyandithiocarbamic acid (melting point: 112°C) has been prepared by reaction between a suspension of K[S₂C? N(CN)₂] in diethyl ether and a solution of HCl in (C₂H₅)₂O at 0°C; the ether was distilled off at 0°C in vacuo. The compound has been characterized by means of infared spectra, electron absorption spectra, ¹H-NMR spectra, and mass spectra. The dissociation constant of N-dicyandithiocarbamic acid in water is K_a = (1.69 ± 0.1) X 10^?1 20°C. The thermodynamic data of the dissociation were calculated.     

Charakterisierung und katalytische Aktivität von Ni2+-ausgetauschten X- und Y-Zeolithen. II. Die Reduzierbarkeit des Ni2+ durch niedere Olefine und die Dimerisierungsaktivität der Ni2+-ausgetauschten Zeolithe

Characterization and Catalytic Activity of Ni²⁺ -X and -Y Zeolites. II. Reducibility of Ni²⁺ by Low Olefines and the Dimerization Activity of the Ni²⁺ -Zeolites The reducibility of Ni²⁺ in X and Y zeolites by hydrogen, but-1-ene, propene, and ethene is compared. The degree of reduction was determined after isothermal reduction and reoxidation by the TPR method. At 673 K on X zeolites the reducibility decreases in the order: H₂ > but-1-ene, propene > ethene. On Y zeolites an inversion takes place: but-1-ene, propene > H₂, ethene. The mechanism of reduction by olefins should be determined by an intermediate splitting off of a hydride ion as a reducing species. Such a mechanism explains the higher degree of reduction in the more acid Y zeolites. Assuming low valent nickel as an active center in ethen dimerization the induction period results from the reduction of Ni²⁺ ions.     

Über die Darstellung von Phosphoniumsalzen aus Yliden und den freien Säuren bzw. ihren Ammoniumsalzen

The Synthesis of Phosphonium Salts from Ylids and Free Acids or Their Ammonium Salts Tetramethylphosphonium-acetate, -hydrogendiacetate, -azide, -thiocyanate, -nitrate, -sulfate, and -thiosulfate have been prepared from trimethylmethylene phosphorane and the corresponding acids or their ammonium salts, with liberation of ammonia. The reactions were conducted in inert solvents or in alcohol/water mixture and yield pure products in high yields.     

Massenspektrometrische Untersuchung von Bromiden: Über den Einfluss der Radikalstabilität auf die Ringgrösse Cyclischer Bromonium-Ionen

The existence of 5- or 6-membered cyclic bromonium ions, produced from ω-phenyl alkyl bromides under electron-impact conditions, is decisively dependent upon the stability of the phenyl alkyl radicals.     

Über Chalkogenolate. 85. Untersuchungen über Halbester der Trithiokohlensäure 3. Schwingungsspektren von Alkylthioxanthogensäuren und Wasserstoffbrücken in den freien Säuren

On Chalcogenolates. 85. Studies on Hemiesters of Trithiocarbonic Acid 3. Vibrational Spectra of Alkyl Thioxanthic Acids and Hydrogen Bondings in the Free Acids The IR spectra of alkyl thioxanthic acids RS? CS(SH) with R = CH₃, C₂H₅, ⁿC₃H₇, ⁱC₃H₇, ⁿC₄H₉, ^sC₄H₉, ^tC₄H₉, and CH₃S? CS(SD) as well as the Raman spectrum of the Compound with R = CH₃ have been assigned. The formation of hydrogen bondings in the free acids has been studied by means of i.r. spectra, ¹H-n.m.r. spectra, and electron absorption spectra. The energies of the hydrogen bondings have been calculated.