ISSN:
0044-2313
Keywords:
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Description / Table of Contents:
Drei Bromide des Lanthans: LaBr2, La2Br5 und LaBr3Farbloses LaBr3 wurde durch Umsetzung von La2O3 mit NH4Br bzw. in einkristalliner Form durch chemischen Transport mit AlBr3 erhalten. Schwarze Einkristalle von LaBr2 und La2Br5 wachsen aus der Schmelze, die man bei der metallothermischen Reduktion von LaBr3 mit Lithium erhält (verschweißte Tantalampulle, 850°C). Die Kristallstrukturen der drei Lanthanbromide wurden verfeinert: LaBr2. 2H2-Typ, hexagonal (P63/mmc); a = 409,88(4) pm; c = 1 390,0(1) pm; R = Rw = 0,092; La2Br5. Pr2I5-Typ, monoklin (P21/m); a = 789,09(6) pm; b = 424,89(4) pm; c = 1342,3(1) pm β = 91,60(1)º; R = 0,067; Rw = 0,055; LaBr3. UCl3-Typ, hexagonal (P63/m) a = 797,13(4) pm; c = 452,16(4) pm; R = 0,036; Rw = 0,032.
Notes:
Colourless LaBr3 was obtained via the ammonium-bromide route and in singlecrystalline form by chemical vapour-phase transport with aluminium tribromide. Black single crystals of LaBr2 and La2Br5 have been grown from the melts that are obtained by lithium reduction of lanthanum tribromide in sealed tantalum ampoules at 850°C. The crystal structures of the three bromides of lanthanum were refined: LaBr2. 2H2-MoS2 type, hexagonal (P63/mmc), a = 409.88(4) pm, c = 1390.0(1) pm, R = Rw = 0.092; La2Br5. Pr2I5 type, monoclinic (P21/m), a = 789.09(6) pm, b = 424.89(4) pm, c = 1342.3(1) pm, β = 91.60(1)º, R = 0.067, Rw = 0.055; LaBr3. UCl3 type, hexagonal (P63/m), a = 797.13(4) pm, c = 452.16(4) pm, R = 0.036, Rw = 0.032.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/zaac.19895750109
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