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  • Crystal structure  (6)
  • Dimer absorption  (2)
  • ESR spectroscopy  (2)
  • 1
    Digitale Medien
    Digitale Medien
    Die Kristallstruktur des Calciumazid-Dihydrates (1988)
    Springer
    Monatshefte für Chemie 119 (1988), S. 921-927 
    Details
    ISSN: 1434-4475
    Schlagwort(e): Azide ; Calcium ; Crystal structure ; Dihydrate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Single crystals of Ca(N3)2·2 H2O have been prepared from aqueous solutions at room temperature. The crystals are monoclinic,a=1 159.0 (3),b=614.2 (2),c=785.5 (2) pm, β=106.52 (2)°,Z=4, space group P21/n. The crystal structure was determined by single crystal X-ray diffraction (1 109 Mo-Kα-reflexions,R=0.052). Calcium atoms are surrounded by four azide groups and four water molecules. The coordination polyhedra are antiprism which are sharing azide groups and water molecules to form layers. The lattice constants and powder pattern agree well with values reported earlier for Ca(N3)2 · 1.5 H2O [1]. It was also shown, that Sr(N3)2 · 2 H2O is isotypic with Ca(N3)2 · 2 H2O.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00810101
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  • 2
    Digitale Medien
    Digitale Medien
    Kristallstrukturen von drei Addukten des Zinkazides mit Dimethylpyridinen (1992)
    Springer
    Monatshefte für Chemie 123 (1992), S. 325-331 
    Details
    ISSN: 1434-4475
    Schlagwort(e): Azide ; Crystal structure ; Dimethylpyridine ; Zinc
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Three adducts of zinc azide with 2,4-/3,4- and 3,5-dimethylpyridine (DMP), respectively, were prepared and the crystal structures determined by single crystal X-ray diffraction methods. The three compounds crystallize in the monoclinic space group P21/c withZ=4: Zn(N3)2·2,4-DMP at 300 (2) K:a=1 098.6(4),b=1 600.2(6),c=608.8(3) pm, β=102.47(3)°;R=0.071 (R w =0.056). Zn(N3)2·3,4-DMP at 103 (3) K:a=1 102.1(3),b=1 649.0(4),c=611.8(1) pm, β=104.54(2)°;R=0.055 (R w =0.051). Zn(N3)2·3,5-DMP at 97 (3) K:a=602.1(2),b=2 037.9(7),c=853.8(3) pm, β=90.77(3)°;R=0.069 (R w =0.055). The molecular geometry is similar for the three adducts, but the packing of theDMP-molecules is different. The zinc atoms are surrounded by five nitrogen atoms, four belonging to the azide groups and one to theDMP-adduct. The trigonal bipyramidal shaped ZnN5-polyhedra share common edges to form chains.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00810944
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  • 3
    Digitale Medien
    Digitale Medien
    Low-temperature structural phase transition in SrMo6S8 studied by X-ray powder diffraction (1990)
    Springer
    Monatshefte für Chemie 121 (1990), S. 505-509 
    Details
    ISSN: 1434-4475
    Schlagwort(e): Chevrel phases ; Crystal structure ; Phase transition ; X-ray analysis ; Rietveld refinement ; Powder diffraction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Die Temperaturabhängigkeit der Gitterparameter und die Atomlagen der Tieftemperaturphase von SrMo6S8 wurden mittels Röntgenpulverdiffraktometrie bestimmt. Die rhomboedrische Hochtemperaturmodifikation (R $$\bar 3$$ ,a rh=6.5630(3)Å, αrh=88.9982(2)°,V rh=282.55(5)Å3,T=298 K) wandelt beiT 1=135(3) K in die trikline Tieftemperaturmodifikation (P $$\bar 1$$ ,a tr=6.481(1)Å,b tr=6.572(1)Å,c tr=6.611(1)Å, αtr=89.246(4)°, βtr=89.304(4)°, γtr=88.169(4)°,V tr=281.4(2)Å3,T=20 K) um. Die trikline Deformation ist stärker ausgeprägt als in der Ca-Verbindung und ähnlich jener der Ba- and Eu-Verbindung.
    Notizen: Abstract Lattice parameters as a function of temperature for, and atomic coordinates of the low-temperature phase of, SrMo6S8 are reported from X-ray powder diffraction. The structure transforms atT 1=135(3) K from the rhombohedral high-temperature modification (R $$\bar 3$$ ,a rh=6.5630 (3) Å, αrh=88.9982(2)°,V rh=282.55(5)Å3 at 298 K) into the triclinic low-temperature modification (P $$\bar 1$$ ,a tr=6.481(1)Å,b tr=6.572(1)Å,c tr=6.611(1)Å, αtr=89.246(4)°, βtr=89.304(4)°, γtr=88.169(4)°,V tr=281.4(2)Å3 at 20K). The triclinic distortion is larger than in the Ca analogue, and similar to the Ba and Eu analogues.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00810858
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  • 4
    Digitale Medien
    Digitale Medien
    Die Kristallstruktur von Cs5Eu(N3)8 (1990)
    Springer
    Monatshefte für Chemie 121 (1990), S. 781-786 
    Details
    ISSN: 1434-4475
    Schlagwort(e): Azide ; Cesium ; Crystal structure ; Europium ; Rare earth
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The crystal structure of pentacesium octaazidoeuropiate(III), Cs5Eu(N3)8, was determined by single crystal X-ray diffraction: orthorhombic,a=16.811(4),b=16.860(5),c=16.964(3)Å, space group Pbca,Z=8, 2 310 observed reflections,R=0.048. Europium atoms are coordinated to eight azide groups, the coordination polyhedra have no azide groups in common. Four cesium atoms are surrounded by eight, one by seven azide groups. The azide groups are symmetric with mean N-N-distances of 1.17(1)Å.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00808370
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  • 5
    Digitale Medien
    Digitale Medien
    Verfeinerung der Kristallstruktur des Dicaesium-Tetraazido-Zinkates Cs2Zn(N3)4 und die Kristallstrukturen komplexer Zinkazide (1990)
    Springer
    Monatshefte für Chemie 121 (1990), S. 91-97 
    Details
    ISSN: 1434-4475
    Schlagwort(e): Azide ; Cesium ; Crystal structure ; Zinc
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The crystal structure of dicesium-tetraazido-zincate, Cs2Zn(N3)4, has been refined from single crystal X-ray-diffractometer data. The previously reported orthorhombic structure, consisting of isolated Zn(N3)4-tetrahedra was confirmed and improved lattice parameters and atomic distances were determined. The azide groups are asymmetric and the coordination of central nitrogen atoms to cesium was observed. A table of structure data and mean atomic distances for fourteen zinc-azide compounds is added and the structures are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00809520
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  • 6
    Digitale Medien
    Digitale Medien
    Die Kristallstruktur eines polynuklearen Co(II)-Komplexes in Cs2[Co3(N3)8] (1988)
    Springer
    Monatshefte für Chemie 119 (1988), S. 509-514 
    Details
    ISSN: 1434-4475
    Schlagwort(e): Azide ; Cesium ; Cobalt ; Complex ; Crystal structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Cs2[Co3(N3)8] crystallizes monoclinic,a=1 123.8 (3),b=568.4 (2),c=1 542.6 (4) pm, β=107.37 (2)°, space group P21/n,Z=2. The crystal structure was determined by single crystal X-ray diffraction,R w=0.069. Coatoms are coordinated octahedrally to six azide groups and form polynuclear complexes of composition [Co3(N3)8]2−. The complex anions share edges and are connected to infinite chains running along theb-axis direction. Cesium is irregularly surrounded by azide groups.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00809202
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  • 7
    Digitale Medien
    Digitale Medien
    On the Homoconjugation of Two Acceptor Groups (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 1615-1623 
    Details
    ISSN: 1434-193X
    Schlagwort(e): Homoconjugation ; Cyclovoltammetry ; ESR spectroscopy ; Diketones ; Heterocycles ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Cyclovoltammetric investigations have been carried out on 3,3,6,6-tetramethylcyclohexane-1,2,4,5-tetrone (4), bicyclo-[3.2.2]nonane-6,7,8,9-tetrone (5), and several of their congeners, such as 6,13-dihydro-6,6,13,13-tetramethylquin-oxalino[2.3-b]phenazine (13), 5,10-dihydro-5,5,10,10-tetra-methylpyrazino[2,3-g]quinoxaline (17), and 6,13-dihydro-6,13-propanoquinoxalino[2,3-b]phenazine (20). For 5 and 20 a large difference (ΔE° ≥400 mV) between the first and second reduction potentials was found. The ESR results of the radical anion 20•- are in support of a strong homoconjugation. ESR studies of 4•-, 13•-, and 17•- also reveal a symmetrical displacement of the unpaired electron over both acceptor groups on the ESR time scale which, however, based on the small potential difference ΔE° ≤ 200 mV can be most likely described to a fast electron exchange.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Phenazin-5(10H)-yls, 5Part 4: Ref[1].. - Intermolecular π-π Interactions (Pimerization) of tert-Butyl-Substituted Phenazin-5(10H)-yl Radicals in The Solid State: Syntheses, Crystal Structures and Magnetic Susceptibility Measurements (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 473-483 
    Details
    ISSN: 0947-3440
    Schlagwort(e): Phenazin-5(10H)-yl ; ESR spectroscopy ; Radical pairs ; π Interactions ; Dimer absorption ; Magnetic susceptibility ; Nitrogen heterocycles ; Radicals ; Magnetic properties ; Solid-state chemistry ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Introduction of tert-butyl groups into the phenazine frame-work was accomplished by treatment of 5-acetyl-5,10-dihydrophenazine (2a) with tert-butyl chloride in the presence of AlCl3. Starting from the 2,8- or 3,7-di-tert-butyl-substituted derivatives 2c and 2b, a series of phenazin-5(10H)-yl radicals (1c-i) was synthesized and characterized by ESR and EN-DOR spectroscopy. With the exception of 1c, all phenazin-5(10H)-yls were obtained in crystalline form, and for 1d-f the long-wavelength absorption band at λ ≈ 870 nm indicates intermolecular π-π interactions in the solid state. For 1d, 1e and 1h the crystal structure could be determined. The unit cell of 1d consists of eight phenazin-5(10H)-yls. Surprisingly, four of them are arranged in radical pairs, whereas the other four lie independently in the lattice. In agreement with this structure, the magnetic susceptibility results correspond to a content of 50% monoradical and an almost complete spinpairing in the radical pairs up to T = 220 K. In 1e, the four phenazin-5(10H)-yls in the unit cell are arranged in two independent radical pairs, A and B, which are characterized by close interplanar distances and short intermolecular contacts between atoms with significant spin populations. Accordingly, the susceptibility data indicate strong spin-pairing at low temperature. Due to extensive steric shielding of the phenazin-5(10H)-yl framework, the crystal structure of 1h gives no evidence of any π-π interactions between adjacent radicals. As expected, the magnetic susceptibility of 1h corresponds to that of an ordinary monoradical.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jlac.199719970307
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  • 9
    Digitale Medien
    Digitale Medien
    Phenazin-5(10H)-yls, 4Parts 1-3: Ref.. 10-Ethylphenazin-5(10H)-yl · H2O: Crystal Structure, Magnetic Susceptibility and Intermolecular π-π Interactions (Pimerization)Dedicated to Professor Rolf Gleiter on the occasion of his 60th birthday. (1996)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1996 (1996), S. 1867-1870 
    Details
    ISSN: 0947-3440
    Schlagwort(e): Phenazin-5(10H)-yl radicals ; Radical pairs ; π-π-Interactions ; Pimerization ; Dimer absorption ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The unit cell of 10-ethylphenazin-5(10H)yl · H2O consists of eight phenazin-5(10H)-yls that are arranged in four independent radical pairs A-D. All pairs show close interplanar distances (3.28-3.36 Å). Furthermore, A, B, and D are characterized by short intermolecular contacts between atoms with significant spin populations. This is not valid for the pair C with the closest interplanar distance of 3.28 Å. Magnetic susceptibility measurements as a function of temperature indicate complete spin pairing (“pimerization”) between 20 and 100 K. Therefore, the radical pair C provides evidence that unspecific close interplanar contacts together with a reasonable overlap of the π systems are sufficient to lead to pimerization.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jlac.199619961121
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