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  • 1
    Electronic Resource
    Electronic Resource
    Detection of free radicals in living mice after inhalation of DTBN by X-band ESR
    Amsterdam : Elsevier
    Free Radical Biology and Medicine 14 (1993), S. 339-342 
    Details
    ISSN: 0891-5849
    Keywords: DTBN disposition in mice ; EPR ; ESR ; Free radicals-Detection in living mice ; In vivo ; Inhalation of DTBN
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0891-5849(93)90030-X
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  • 2
    Electronic Resource
    Electronic Resource
    Zu Oxoiridaten mit quadratisch-planaren [IrO4]4--Gruppen: Na4IrO4, eine MgO-Ersetzungsvariante mit geordneten Lücken im Anionenteilgitter (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 1647-1654 
    Details
    ISSN: 0044-2313
    Keywords: Oxoiridate(IV) ; square planar groups ; MAPLE calculation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Oxoiridates(IV) with Square-planar Groups [IrO4]4-: Na4IrO4, a Substitution-variant of MgO with Ordered Vacancies in the Anionic Part of Structure.For the first time we prepared transparent red single crystals of Na4[IrO4] by an “exchange reaction” (Li2IrO3 + 2.20 Na2O; Ag, 800°C, 71 days): tetragonal, space group I4/m (No. 87), a = 716.70(4) pm and c = 471.32(4) pm; Z = 2.The structure determination via four circle diffractometer data (Mo—Kα, graphite; 2 138 I0(hkl), R = 0.0179; Rw = 0.0184) was carried out with all 296 independent reflexions.Therefore Na4IrO4 crystallizes in a defect-variant of MgO which can be derived from Na4UO5. Ir4+ is surrounded square-like by four O2- with two vacancies completing the octahedron.The Madelung Part of Lattice Energy, MAPLE, Effective Coordination Numbers, ECoN, these via Mean Fictive Ionic Radii, MEFIR, are calculated and discussed. Furthermore the mean value for MAPLE(“IrO2”) of all alkaline- and alkaline-earth-oxoiridates(IV) is given.
    Notes: Erstmals erhielten wir über eine Austauschreaktion (Li2IrO3 + 2,20 Na2O; Ag, 800°C, 71 Tage) transparente, rote Einkristalle von Na4IrO4: tetragonal, Raumgruppe I4/m (Nr. 87), a = 716,70(4) pm und c = 471,32(4) pm, Z = 2.Die Struktur wurde mittels Vierkreisdiffraktometerdaten (Mo—Kα, Graphit; 2 138 I0(hkl), R = 0,0179; Rw = 0,0184) unter Verwendung aller 296 symmetrie-unabhängiger Reflexe bestimmt. Na4IrO4 kristallisiert demnach in einer MgO-Defektvariante, die sich vom Na4UO5-Typ ableitet. Ir4+ ist quadratisch-planar von vier O2- umgeben; zwei „Lücken“ ergänzen zum elongierten Oktaeder.Der Madelunganteil der Gitterenergie, MAPLE, Effektive Koordinationszahlen, ECoN, diese über Mittlere Fiktive Ionenradien, MEFIR, werden berechnet und diskutiert. Darüber hinaus wird der Mittelwert für MAPLE(“IrO2”) aller Alkali- und Erdalkalioxoiridate(IV) angegeben.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936191002
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  • 3
    Electronic Resource
    Electronic Resource
    Ein neuer Strukturtyp bei Oxoiridaten mit quadratisch-planaren [IrO4]4--Gruppen: K2Na2[IrO4], ein Raumnetz ∞3[Na2IrO4] mit Kanälen. (Mit einer Anmerkung zu Rb2Na2[IrO4]) (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 225-233 
    Details
    ISSN: 0044-2313
    Keywords: Oxoiridates ; [IrO4]4- groups ; crystal structure ; magnetic measurements ; MAPLE calculation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A New Type of Structure in Oxoiridates with Square-planar Groups [IrO4]4-: K2Na2[IrO4], a Network ∞3[Na2IrO4] with Channels (With a Remark on Rb2Na2[IrO4])For the first time magnificent dark red cuboid single crystals of K2Na2[IrO4] were prepared by annealing intimate mixtures of a) KO0.51, Na2O2, IrO2 and Ir-powder (molar proportions 3.02 : 1.40 : 1.00 : 1.00; Ag-bomb, 740°C, 54 d) and of b) KO0.51, Na2O and IrO2 (molar proportions K : Na : Ir = 2.20 : 2.20 : 1.00; Ag-bomb, 760°C, 57 d) respectively. The oxide crystallizes mP36, space group P21/c with a = 600.35(6) pm, b = 1111.2(1) pm, c = 933.0(1) pm and β = 113.14(1)°.Structure determination via four-circle diffractometer data (Siemens AED 2, Mo-Kα-Radiation) for all 2347 unique reflexions (merged from 9397 Io(hkl) gave R = 0.0357 and Rw = 0.0340. K2Na2[IrO4] crystallizes in a new type of structure. The oxide is antiferromagnetic as magnetic measurements showed (TN = 32 K, Θ = -60.2 K (single crystals) and -49.2 K (powder) respectively, μ = 3.06 μB (single crystals) and 2.93 μB (powder) respectively).Effective coordination numbers ECoN, mean fictive ionic radii MEFIR and the Madelung part lattice energy MAPLE as well as the charge distributions CHARDI and CHARDINO are calculated and discussed.
    Notes: Erstmals wurde K2Na2[IrO4] durch Tempern inniger Gemenge von (a) KO0,51, Na2O2, IrO2 und Ir-Pulver (molares Verhältnis 3,02 : 1,40 : 1,00 : 1,00; Ag-Bombe, 740°C, 54 d) bzw. (b) KO0,51, Na2O und IrO2 (molares Verhältnis K : Na : Ir = 2,20 : 2,20 : 1,00; Ag-Bombe, 760°C, 57 (d) in Form prächtiger, dunkelroter, quaderförmiger Einkristalle erhalten. Das Oxid kristallisiert in P36, Raumgruppe P21/c mit a = 600,35(6) pm; b = 1111,2(1) pm; c = 933,0(1) pm und β = 113,14(1)°. Die Struktur wurde anhand von Vierkreisdiffraktometerdaten aufgeklärt (Siemens AED 2, Mo-Kα-Strahlung, Graphit). Für alle 2347 symmetrieunabhängigen Reflexe (gemittelt aus 9397 gemessenen Io(hkl)) war schließlich R = 0,0357 und Rw = 0,0340. K2Na2[IrO4] kristallisiert in einem neuen Strukturtyp. Magnetische Messungen zeigten, daß das Oxid antiferromagnetisch ist (TN = 32 K, Θ = -60,2K (Einkristalle) bzw. -49,2K (Pulver); μ = 3,06 μB (Einkristalle) bzw. 2,93 μB (Pulver)).Effektive Koordinationszahlen ECoN, Mittlere Fiktive Ionenradien MEFIR und der Madelunganteil der Gitterenergie MAPLE sowie die Ladungsverteilungen nach CHARDI und CHARDINO werden berechnet und diskutiert.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19946200206
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  • 4
    Electronic Resource
    Electronic Resource
    EPR study of β-methylene proton magnetic inequivalence in monomeric addition radicals derived from mono- and 1,1′-disubstituted ethylenes with chiral and non-chiral substituents (1995)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 33 (1995), S. 395-405 
    Details
    ISSN: 0749-1581
    Keywords: EPR ; Proton magnetic inequivalence ; chirality effects ; addition radicals ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using rapid-mixing, continuous-flow TiCl3-based techniques at 25°C monomeric addition radicals of general formula ·CX(Y)CH2C*HR1R2, where R1 and R2 are different groups, neither being H, so that C* is a chiral center, were characterized by electron paramagnetic resonance. These species were generated by adding ·CH(CH3)OH, CH(CH3)OCH2CH3,.CH(CH3)OC(O)H,.CH(CH3)OC(O)CH3 and radicals in turn to each of the monomers, of general structure CX(Y)=CH2, acrylonitrile, acrylic acid, tert-butyl acrylate, butyl acrylate, methacrylonitrile, methacrylic acid, itaconic acid and but-3-ene-1,2,3-tricarboxylic acid. Similar reactions of carbon-centered radicals with vinyl fluoride and 1,1-difluoroethylene did not yield detectable levels of the expected addition radicals. In every addition radical observed, the splittings of the β-CH2 protons were found to be unequal and the size of this inequivalence varied qualitatively with the bulkiness of X, Y, R1 and R2. Similar measurements on monomeric addition radicals of general formula.CX(Y)CH2Z, where Z is achiral, generated in turn from the same monomers by adding.OH,.NH2 and, showed no evidence for the β-CH2 proton splittings to be unequal. These results demonstrate the importance of an awareness of chirality effects in interpreting EPR spectra of monomeric and polymeric addition radicals of mono- and 1,1′-disubstituted ethylenes.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260330512
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