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. IV. Über Struktur und Aktivität der den H2O2-Zerfall katalysierenden Cu2+-Komplexe. II. Einfluss der Zahl der freien Koordinationsstellen

The Cu²⁺ chelates of the bidentate ligands 2,2′-bipyridine (I; [2]), N, N′-diglycyl-1,5-diaminopentane (VI), ethylenediamine (II; [2]), glycine (V) and pyrophosphate (III; [2]) are found–parallel to the spectrochemical series–to be more active in catalysis of H₂O₂ decomposition than the chelates of the terdentate ligands–antiparallel to the spectrochemical series–iminodiacetic acid (IX), glycylglycine (VIII), 2, 2′-diaminodiethylamine (VII) and 2, 2′, 2″-terpyridine (IV; [2]), the activity decreasing in the given series. If all four coordination positions of Cu²⁺ are engaged (e.g. complex with N, N′-di-(2-aminoethyl)-ethylenediamine (X)) the complex is inactive. The catalytic activity of the Cu²⁺-chelates is parallelled by the tendency to form ternary peroxo complexes.     

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.     

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 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.     

Charakterisierung und katalytische Aktivität von Ni2+-ausgetauschten X- und Y-Zeolithen. I. TPR-Untersuchungen an NiNaX- und NiNaY-Zeolithen

Charaterization and Catalytic Activity of Ni²⁺ Exchanged X and Y Zeolites. I. TPR Studies on NiNaX and NiNaY Zeolites . The structure of TPR spectra of NiNaX and NaNiY zeolites variously exchanged is determined by the location of the cations. In case of X zeolites a peak appears with a maximum at 750–800 K (reduction on S_II and S_I, positions) and for higher exchange degrees an additional one at about 1000 K (reduction on S_I positions). Three ranges of reduction may be separated in case of Y zeolites (reduction on S_II, S_I′, and S_I). With increasing Si/Al ratios the maximum of the hightemperature peak is shifted to higher temperatures. The reduction at temperatures up to 800 K resulted in higher reduction degrees for X reolites while the overall reduction up to high temperatures led to higher reduction degrees for Y zeolites. The kinetic analysis by means of two different methods yielded the following activation energies: (85 ± 10) or (86 ± 2) kJ/mole, respectively, for the low-temperature peak, and (223 ± 12) or (214 ± 2) kJ/mole, respectively, for the high-temperature peak.     

Homogene Lösungskatalyse. Über die Hemmwirkung von La3+-Ionen im H2O2-Zerfall in homogener Lösung

The inhibitor action of La³⁺ ions on the H₂O₂ decomposition has been proved in NaHCO₃ containing solution.     

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 den zusammenhang von linienintensität und elementkonzentration im optisch dünnen bogenplasma

Based on a simple model of the free burning constant current arc (rectangular temperature pattern, no self-absorption), the intensity ratio of a line pair (analytical line/internal standard line) is investigated as a function of the analytical element concentration in the plasma. Assuming the concentration in the plasma to be unequivocally determined by the element concentration in the sample, the intensity-concentration relationships may be interpreted as working curves. It appears that these theoretical working curves are generally not linear and the slopes may deviate significantly from unity when plotted in logarithmic coordinates. The shapes of the working curves depend on parameters characteristic of the line pair under consideration (excitation and ionization energies, partition functions) as well as on the temperature and electron-density and their changes. The results obtained are illustrated by a calculated example.