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  • 1
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The cross-polarization/magic-angle-spinning (CP/MAS) 77SeNMR experiment of Ph-Se-Se-Ph affords two signal series with isotropic chemical shifts at δiso = 425 and 350. IGLO calculations allow to assign the 77Se signals and to predict the orientation of the shielding tensors. The different chemical shifts can be explained by different torsion angles Se-Se-Cipso-Cortho which produce different β effects of the phenyl rings upon the respective next but one selenium atom.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0044-2313
    Keywords: Lithium ; Rare Earth Halides ; Crystal Structures ; Ionic Motion ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Ternary Halides of the A3MX6 Type. VI. Ternary Chlorides of the Rare-Earth Elements with Lithium, Li3MCl6 (M = Tb—Lu, Y, Sc): Synthesis, Crystal Structures, and Ionic MotionSingle crystal X-ray studies on the ternary chlorides Li3ErCl6, Li3YbCl6 and Li3ScCl6 show that they crystallize in three different structure types. Li3ErCl6 (trigonal, P3ml, Z = 3, a = 1117.7(2); c = 603.6(2) pm; the chlorides with M = Tb—Tm, Y are isotypic) and Li3YbCl6 (orthorhombic, Pnma, Z = 4, a = 1286.6(1); b = 1113.2(1); c = 602.95(8) pm; Li3LuCl6 is isotypic) have very similar structures that may be derived from hexagonal closest packings of chloride ions with the cations occupying octahedral holes in part statistically. Li3ScCl6 (monoclinic, C2/m, Z = 2, a = 639.8(1); b = 1104.0(2); c = 639,1(1) pm; β = 109.89(1)°) crystallizes isotypic with Na3GdI6 and Li3ErBr6, structures that may be derived from a cubic closes packings of anions. The ionic movement in Li3YCl6 and Li3YbCl6 has been investigated by impedance and 7Li-NMR spectroscopy.
    Notes: Die ternären Chloride Li3ErCl6, Li3YbCl6 und Li3ScCl6 kristallisieren nach röntgenographischen Untersuchungen an Einkristallen in drei verschiedenen Strukturtypen. Li3ErCl6 (trigonal, P3ml, Z = 3, a = 1117,7(2); c = 603,6(2) pm; isotyp mit M = Tb—Tm, Y) und Li3YbCl6 (orthorhombisch, Pnma, Z = 4, a = 1286,6(1); b = 1113,2(1); c = 602,95(8) pm; Li3LuCl6 ist isotyp) haben sehr ähnliche Strukturen, die sich als hexagonal-dichteste Kugelpackungen von Chlorid-Ionen mit zum Teil statistischer Auffüllung der Oktaederlücken mit Kationen beschreiben lassen. Li3ScCl6 (monoklin, C2/m, Z = 2, a = 639,8(1); b = 1104,0(2); c = 639,1(1) pm; β = 109,89(1)°) kristallisiert isotyp mit Na3GdI6 und Li3ErBr6; die Anionen bilden hier eine kubisch-dichteste Kugelpackung. Die Ionenbewegung in Li3YCl6 und Li3YbCl6 wurde mittels Impedanzspektroskopie und 7Li-NMR-Spektroskopie untersucht.
    Additional Material: 5 Ill.
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  • 3
    ISSN: 0044-2313
    Keywords: Lithium Niobium Chloride ; Niobium Cluster ; Synthesis ; Crystal Structure ; Lithium mobility ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese, Struktur und Eigenschaften von LiNb6Cl15Schwarze Einkristalle von LiNb6Cl15 wurden aus Reaktionen von Nb-Pulver, NbCl5 und LiCl in verschweißten Niobrohren bei 850°C hergestellt. Die Schweratomstruktur von LiNb6Cl15 (Ia3d (Nr. 230), Z = 16, a = 2055.5(2) pm at 100 K, R(F) = 0.028, R(F2) = 0.053) ist mit der Struktur von Ta6Cl15 isotyp. Die [Nb6Cl12]2+-Cluster sind in der Struktur dreidimensional über drei zusätzliche Cla-a verbrückt. Diese verbrücken alle Ecken der Niobcluster, entsprechend der Schreibweise [Nb6Cl12iCl6/2a-a]- (die Nb—Cla-a—Nb-Bindungswinkel betragen 140°). Bei tiefen Temperaturen sind die Lithiumionen über ein Drittel von Lagen (48 f) fehlgeordnet und besetzen Hohlräume in verzerrten Chlorid-Tetraedern, die eine gemeinsame Kante teilen. Diese Positionen der Lithiumionen repräsentieren die engsten Stellen der unendlichen Kanäle in der Struktur, die von Chlorid gebildet werden. 7Li-NMR-Messungen zeigen oberhalb von 170 K eine deutliche Zunahme der Lithiumionenbeweglichkeit.
    Notes: Black single crystals of LiNb6Cl15 were obtained from reactions of Nb powder, NbCl5 and LiCl in sealed niobium tubes at 850°C. The heavy atom structure of LiNb6Cl15 (Ia3d (no. 230), Z = 16, a = 2055.5(2) pm at 100 K, R(F) = 0.028, R(F2) = 0.053) is isotypic with the structure of Ta6Cl15. The [Nb6Cl12]2+ clusters in the structure are three-dimensionally interconnected via three additional Cla-a. These bridge all vertices of niobium clusters, consistent with [Nb6Cl12iCl6/2a-a]- (the Nb—Cla-a—Nb angles are 140°). At low temperatures the lithium ions are disordered over one-third of sites (48 f), occupying cavities inside of two distorted corner-sharing tetrahedra of chloride. These positions for lithium represent the narrowest sections of infinite channels in the structure built up by chloride. An increased lithium ion mobility is obtained above 170 K by 7Li-NMR measurements.
    Additional Material: 7 Ill.
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  • 4
    ISSN: 0044-2313
    Keywords: Lithium ; Rare Earth Halides ; Crystal Structure ; Ionic Conductivity ; NMR Spectroscopy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Ternary Halides of the A3MX6Type. VII. The Bromides Li3MBr6 (M=Sm—Lu, Y): Synthesis, Crystal Structure, and Ionic MobilityThe bromides Li3MBr6 (M=Sm—Lu, Y) are obtained from the binary components LiBr and MBr3. They crystallize with a substitution/addition variant of the AlCl3- type of structure as was established from single crystal X-ray diffraction data for Li3ErBr6 (monoclinic, C2/m, Z = 2, a = 689.0(3), b = 1191.6(9), c = 684.2(6) pm, β = 109.77(6)°) and by powder X-ray diffraction for the remaining bromides. They are isotypic with Na3GdI6 and Li3ScCl6, respectively. Impedance spectroscopy and 7Li-NMR spectroscopy show that the lithium ions are highly mobile.
    Notes: Die Bromide Li3MBr6 (M=Sm—Lu, Y) erhält man durch Umsetzung der binären Komponenten LiBr und MBr3. Sie kristallisieren in einer Substitutions-Additions-Varianten des AlCl3-Typs, was anhand von röntgenographischen Untersuchungen an einem Einkristall von Li3ErBr6 (monoklin, C2/m, Z = 2, a = 689,0(3); b = 1191,6(9); c = 684,2(6) pm, β = 109,77(6)°) sowie an Pulverproben der übrigen Bromide nachgewiesen wurde. Sie sind isotyp mit Na3GdI6 bzw. Li3ScCl6. Impedanzmessungen und 7Li-NMR-Messungen an Pulverproben zeigen eine hohe Mobilität der Li+-Ionen.
    Additional Material: 3 Ill.
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