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  • 1
    ISSN: 1433-0768
    Keywords: Key words Solid state electrochemistry ; Mössbauer ; Magnetic susceptibility ; X-ray powder diffraction ; Iron(III)-cadmium(II) hexacyanoferrates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Coprecipitates of CdII, KI and FeIII with hexacyanoferrate ions [Fe(CN)6]4− have been studied by solid-state electrochemistry (voltammetry of immobilized microparticles), magnetic susceptibility measurements, X-ray powder diffraction, electron spin resonance, Mössbauer and diffuse reflectance spectroscopy. Most suprisingly, all experimental results point to the formation of a continuous series of complex mixed phases without the formation of phase mixtures. Although CdII and FeIII ions differ too much in their ionic radii to allow the formation of simple substitution mixed hexacyanoferrates, they are capable of forming different kinds of complex insertion and substitution mixed crystals because of the zeolitic structure of both the iron and the cadmium hexacyanoferrate. Low cadmium concentrations can be found in the zeolitic cavities of iron hexacyanoferrate (Prussian blue), and they start to widen the lattice and facilitate, at higher concentrations, the direct substitution of high-spin iron(III) ions by cadmium ions. In cases of an excess of cadmium, the formation of cadmium hexacyanoferrate with iron(III) ions in the interstitials of the zeolitic structure is observed. These mixed phases show strong charge transfer bands in the visible range and have the appearance of “diluted” Prussian blue. For the first time, this indicates that the charge transfer between the carbon-coordinated low-spin iron(II) ions and the high-spin iron(III) ions can also occur when the latter are situated in the cavities of a host hexacyanoferrate. In Prussian blue the interstitial iron(III) ions are responsible for a very strong charge transfer interaction between the low-spin iron(II) ions and the nitrogen-coordinated high-spin iron(III) ions. Upon substitution of the very small amount of interstitial iron(III) ions in Prussian blue by potassium and cadmium ions the Kubelka-Munk function diminishes by more than 30%, indicating a tremendous decrease in iron(III)-iron(II) interaction.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 405 (1974), S. 286-298 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: ESR Studies of Radiation Processes in Phosphate GlassesRadiation processes in phosphate glasses are investigated by ESR and optical measurements. ESR shows a hole-centre in the systems K2O/P2O5 and K2O/MGO/P2O5 which depends on manner and concentration of the cations. Its nature is explained in somewhat a different way than given by BEEKENKAMP or by MIURA and HASEGAWA. Another hole-centre which is independent of cations is discussed in agreement with optical investigations. The electrons set free by radiation react with O2 solved in the glass or with cations. The particels Ag0, Ag2+, Ag+2 have been found and Agn+4 may be present too in the system K2O/MgO/Ag2O/P2O5. The system K2O/MgO/Tl2O/P2O5 shows analogous reactions, but full explanation of the lines could not yet be given.
    Notes: Durch ESR-Untersuchungen und Vergleiche mit optischen Messungen werden Aussagen über die durch Bestrahlung in Phosphatgläsern ablaufenden Vorgänge gemacht. In den Systemen K2O/P2O5 und K2O/MgO/P2O5 wird durch ESR-Messungen ein kationenabhängiges Lochzentrum gefunden, dessen Natur in Abweichung von den Modellen nach BEEKENKAMP und nach MIURA u. HASEGAWA erklärt wird. Ein weiteres kationenunabhängiges Lochzentrum wird in Übereinstimmung mit optischen Untersuchungen gedeutet. Die durch Bestrahlung freigesetzten Elektronen lagern sich an im Glas gelösten Sauerstoff (O2) an oder reagieren mit den Kationen. Im System K2O/MgO/Ag2O/P2O5 werden die Teilchen Ag0, Ag2+, Ag+2 gefunden und Agn+4 wahrscheinlich gemacht. Für das System K2O/MgO/Tl2O/P2O5 gelten analoge Verhältnisse. Eine ausführliche Zuordnung konnte aber dabei noch nicht vorgenommen werden.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 472 (1981), S. 220-232 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: EPR Studies of Caminau Kaolin, its Heating Products, and of the Chlorination Products of MetakaolinEPR-spectra of kaolin, metakaolin and of the heating and chlorination products of metakaolin have been measured and partially interpreted. Fe3+ ions are found in kaolin in at least five different coordination conditions. Coordination changes of Fe3+ ions by heating kaolin and tempering metakaolin are reflected sensitively in the EPR spectra. Correlations between EPR spectra of the solid not fluidable chlorination residues and chlorination conditions have been found.
    Notes: Es wurden die EPR-Spektren von Kaolin, Metakaolin sowie von dessen Temper- und Chlorierungsprodukten aufgenommen und z. T. interpretiert. Im Kaolin befinden sich Fe3+-Ionen in mindestens fünf verschiedenen Koordinationszuständen. Die beim Erwärmen des Kaolins, bei dessen Calcinierung sowie beim Tempern des Metakaolins eintretenden Veränderungen werden in den EPR-Spektren empfindlich widersgepiegelt. Zwischen den EPR-Spektren der festen Chlorierungsrückstände und den Chlorierungsbedingungen wurden Zusammenhänge gefunden.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 515 (1984), S. 230-240 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Existence and Structure of Secondary DithizonatesOn example of complexation with copper and palladium proved, that dithizone by double deprotonation forming neutral “secondary” dithiozonates, which have been characterized by elemental analyses, electronic, i.r., ESCA, and EPR spectra and magnetic measurements. Dithizone reacts about ligator atoms N,N′,S. Secondary dithizonates probable are present dimeric.
    Notes: Am Beispiel der Komplexbildung mit Kupfer und Palladium wird nachgewiesen, daß Dithizon unter zweifacher Deprotonierung neutrale, „sekundäre“ Dithizonate bildet, die durch Elementaranalyse, VIS-, IR-, EPR- und Photoelektronen-Spektren sowie magnetische Messungen charakterisiert werden. Dithizon wirkt über die Ligatoratome N,N′,S. Die sekundären Dithizonate liegen wahrscheinlich dimer vor.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 532 (1986), S. 204-214 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: About the Coprecipitation of FeIII and CuII with Bismuth Phosphate and Calcium FluorideThe mechanism of FeIII and CuII coprecipitation with BiPO4 and CaF2 as carriers from ammonium phosphate and ammonium fluoride solutions was investigated. Using the radioactive tracers 59Fe and 64Cu and by means of EPR measurements surface adsorption was shown to be main reason causing coprecipitation. Trace metals distribution was possible to be described by means of Henry and Freundlich isotherms. FeIII and CuII are coprecipitated with BiPO4 as counterions to excess phosphate species at the surface. Differences in the behaviour between these metals are of quantitative nature. CuII is coprecipitated with CaF2 as a counterion to excess F-, whereas FeIII adsorption takes place as FeF63- in competition with matrix fluoride.
    Notes: Es wird das Mitfällungsverhalten von FeIII und CuII aus Ammonium-phosphat- bzw. Ammoniumfluorid-Modellösungen mit den durch Anfällen der Matrices erzeugten Kollektorniederschlägen BiPO4 und CaF2 betrachtet. Radiochemische Untersuchungen mit 59Fe und 64Cu und EPR-Messungen machen deutlich, daß in jedem Fall die Adsorption der Spurenmetalle an der Niederschlagsoberfläche Hauptursache ihrer Mitfällung ist. Die Verteilung zwischen Lösung und Niederschlag läßt sich durch Henry- und Freundlich-Isothermen beschreiben. FeIII und CuII werden mit BiPO4 als Gegenionen zu primär adsorbierten Phosphatspezies mitgefällt. Zwischen beiden Metallen treten Unterschiede quantitativer Art auf. Auch die Mitfällung des CuII mit CaF2 erfolgt als Gegenion, hier zu primär adsorbiertem F-. Das FeIII hingegen wird in Konkurrenz zu den Matrixanionen als FeF63- adsorbiert.
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  • 6
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Polarographic Behaviour of Molybdenum(VI) with Special Reference to the Reactions of Molybdenum(V)The reduction of molybdenum(VI) proceeds via molybdenum(V) to molybdenum(III) in sulfuric acid. A dimerization of the formed molybdenum(V) takes place according to a D-mechanism, if hydroxide ligands are involved. The rate of dimerization is large enough to influence the polarographic picture for cH2SO4 〈 2 mol · 1-1 considerably. No experimental reference could be obtained to the existence of molybdenum(IV) during polarography. It was shown, that the preparation of very unstable solutions containing monomeric paramagnetic molybdenum(V) complexes is possible.A summary of the chemical reactions is suggested.
    Notes: Die Reduktion von Molybdän(VI) führt in Schwefelsäure über Molybdän(V) zu Molybdän(III). Enthält das sich zunächst bildende monomere Molybdän(V) Hydroxidliganden, so erfolgt eine Dimerisierung nach dem D-Mechanismus. Diese Dimerisierung ist für cH2SO4 〈 2 mol · 1-1 so schnell, daß das polarographische Bild entscheidend durch diesen Prozeß geprägt wird. Während der Reduktion gibt es keine Hinweise für das Auftreten von Molybdän(IV). Unbeständige Lösungen monomerer paramagnetischer Molybdän(V)-Komplexe konnten erhalten werden.Ein zusammenfassendes Reaktionsschema wird vorgeschlagen.
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  • 7
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Effect of Different Oxidation States of Nickel and Chromium in Heterogenous Halogen ExchangeNi-doted AlF3 catalysts and chromium oxide fluoride catalysts being used for production of C—Cl—F compounds from chlorocarbons by reaction with HF have been investigated by EPR. There are different oxidation states of Ni resp. Cr at the catalysts which show exchange behaviour. Extending the consumptions of mechanisms for heterogeneous Cl—F exchange the oscilation of oxidation state and therefore the exchange in donor-acceptor functions at the catalysts is said to be the cause for the effectiveness of the catalysts. It is presumed that this exchange of oxidation states is of general importance for catalytic processes with heterolytic bond cleavage.
    Notes: Mit der Hilfe von EPR-Messungen wird an Ni-beladenen AlF3-Katalysatoren die Gegenwart von Ni3+ neben chemisch nachgewiesenem Ni2+ und an Chromoxid-Gel-Katalysatoren die Austauschwechselwirkung zwischen CrIII und höheren Oxydationsstufen des Chroms aufgezeigt. Beide Katalysatortypen sin zur Herstellung von C—Cl—F-Verbindungen aus Kohlenstoffchloriden mittels HF geeignet. In Erweiterung von Vorstellungen zum Mechanismus des heterogen-katalytischen Cl—F-Austauschs wird die Oszillation der Oxydationsstufen and damit der Wechsel in Donor-Akzeptor-Funktionen am Katalysator für die Effektivität der Katalysatoren verantwortlich gemacht. Es wird auf die allgemeine Bedeutung dieses Mechanismus hingewiesen.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 563 (1988), S. 185-191 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: EPR Spectra of Soluble Alkylammonium Fluoroferrates(III)The existence of (FeF6)3- has been proved in methanolic solution of alkylammonium fluoroferrates (III) with excess of fluorides. Information about structures of the investigated polycrystalline compounds (NH3CH3)FeF4, (NH3CH3)2FeF5, and (NH3CH3)3FeF6 has been obtained by fitting experimental EPR curves with the help of model functions.
    Notes: In methanolischer Lösung von Alkylammoniumfluoroferraten(III) wird das Vorliegen von (FeF6)3-bei Fluoridüberschuß nachgewiesen. Für die untersuchten polykristallinen Verbindungen (NH3CH3)FeF4, (NH3CH2)2FeF5 und (NH3CH3)3FeF6 werden durch Anpassung von Modellfunktionen an die experimentellen EPR-Spektren Strukturaussagen abgeleitet.
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  • 9
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis, Characterization, and EPR Studies of Heteropoly Compounds with Iron(III) in Tetrahedral and Octahedral CoordinationThe heteropoly compounds H5[FeO4W12O36] · 6 H2O (a0 = 1216 pm), H3[Fe(OH)6Mo6O18] · 4 H2O, Na5[FeO4W12O36] · nH2O and FeH2[FeO4W12O36] · 17 H2O, for the first time obtained in this work by freeze-drying and characterized by means of chemical analysis, i.r. and u.v. spectroscopy, X-ray powder-photographs, and magnetic measurements, appear as suitable model systems for EPR investigations. They contain, like a number of known FeIII-heteropoly compounds, FeIII in FeO4 or/and FeO6 units, which are isolated from each other by structural reasons.In the Keggin-compounds M5[EIIIO4W12O36] · nH2O (I) (M = Na, Rb, TMA, TEA; E = Fe, Al, B) FeIII occupies slightly distorted tetrahedral positions (g′ ≍ 2), which are characterized by zfs-values of ≍ 10 mT and line widthes ΔB of 2.0⃛15 mT. Unlike as for I cations with different physico-chemical characteristics have only little effect on the FeIII-zfs. This holds for the Anderson-complexes M3[Fe(OH)6Mo6O18]·nH2O, (M = H, K, NH4, TMA; g′ ≍ 4.3 ΔB ≍ 67 mT) and for M5[SiO4W11O35FeO5(OH2)]·nH2O, (M = K, TMA; g′ = 4.3 ΔB = 26.5 mT). The FeO6 octahedra are more distorted than the FeO4 tetrahedra in I and therefore less susceptible for structural changes.
    Notes: Die mittels Gefriertrocknung erstmalig synthetisierten und strukturanalytisch charakterisierten Verbindungen H5[FeO4W12O36] · 6 H2O (a0 = 1216 pm), H3[Fe(OH)6Mo6O18] · 4 H2O, Na5[FeO4W12O36] · nH2O und FeH2[FeO4W12O36] · 17 H2O sind zusammen mit einer Reihe bekannter FeIII-haltiger Heteropolyverbindungen geeignete Modellsysteme für die EPR, da sie FeIII in räumlich voneinander weitgehend getrennten FeO4- oder/und FeO6-Struktureinheiten enthalten. In den Keggin-Verbindungen M5[EIIIO4W12O36] · nH2O (I) (M = Na, Rb, TMA, TEA; E = Fe, Al, B) besetzt FeIII gering verzerrte Tetraederplätze (g′ ≍ 2), die durch zfs-Beiträge von etwa 10 mT und Linienbreiten ΔB von 2,0 bis ≍ 15 mT charakterisiert sind. Sowohl in den Verbindungen vom Anderson-Typ M3[Fe(OH)6Mo6O18] · nH2O (M = H, K, NH4, TMA; g′ ≍ 4,3; ΔB ≍ 67 mT) als auch in M5[SiO4W11O35FeO5(OH2)] · nH2O (M = K, TMA; g′ = 4,3; ΔB = 26,5 mT) wirken sich Kationen mit unterschiedlichen physikalisch-chemischen Eigenschaften - anders als bei I - nur in geringem Maße auf die FeIII-zfs aus. Die FeO6-Oktaeder sind stärker verzerrt als die FeO4-Tetraeder in I und damit weniger strukturempfindlich.
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  • 10
    ISSN: 0044-2313
    Keywords: Organonickel(II) complexes ; SO2 coordination ; IR photoacoustic spectroscopy ; X-ray crystal structure of [NiBr{C6H3(CH2NR1R2)2-2,6}] ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Sulfur Dioxide as Ligand and Synthon. XII. Synthesis and Reaction Behaviour of Nickel(II) Complexes with Terdendate Anionic Ligands of the Type (C6H3{CH2NR1R2}2-2,6)-Organonickel(II) complexes of the type [NiX{C6H3(CH2NR1R2)2-2,6}] (X = halide OH2+/CF3SO3-; R1=R2=Et 1; R1=R2=i—Pr 2; R1 = Me, R2 = Cy 3; (NR1R2) = piperidino 4; (NR1R2) = pyrrolidino 5) are described. 1H and 13C NMR and UV/Vis spectra were recorded, and the X-ray crystal structure of 1 a (X = Br) was determined. This complex crystallizes orthorhombically in the space group Pbca with a = 1 335.8(2) pm, b = 1 903.3(3) pm, c = 1 365.4(3) pm and Z = 8, and has an approximately square-planar geometry. 4 and 5 show a reversible binding of SO2 which has been detected by means of IR photoacoustic spectroscopy. The reactions of 1-5 with CS2 and PhNSO are discussed.
    Notes: Organonickel(II)-Komplexe des Typs [NiX{C6H3(CH2NR1R2)2-2,6}] (X = Halogen, OH2+/CF3SO3-; R1=R2=Et 1; R1=R2=i—Pr 2; R1 = Me, R2 = Cy 3; (NR1R2) = piperidino 4; (NR1R2) = pyrrolidino 5) werden beschrieben. Die Charakterisierung erfolgte mit Hilfe der 1H— und 13C-NMR- sowie der UV/Vis-Spektroskopie. Von 1 a (X = Br) wurde die Kristallstruktur bestimmt. Dieser Komplex kristallisiert orthorhombisch in der Raumgruppe Pbca mit a = 1 335,8(2) pm, b = 1 903,3(3) pm, c = 1 365,4(3) pm und Z = 8, er besitzt eine annähernd quadratisch-planare Geometrie. 4 und 5 vermögen SO2 reversibel zu fixieren, was durch die IR-Photoakustik-Spektroskopie nachweisbar ist. Die Reaktionen von 1-5 mit CS2 und PhNSO werden diskutiert.
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