ISSN:
0044-2313
Keywords:
Alkali metal chromium chalcogenides
;
crystal structures
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Description / Table of Contents:
New Alkali Metal Chromium Chalcogenides and their Structural ClassificationThe compounds RbCr3S5, K3Cr11S18, RbCr5Se8 and CsCr5Se8 could be obtained in the form of wellshaped crystals via fusion reactions of the alkali metal carbonates with chromium and the corresponding chalcogen. The compounds crystallize in the monoclinic space groups C2/m (RbCr3S5: a = 19.372(3) Å, b = 3.498(1) Å, c = 12.119(2) Å, β = 122.78(1)°, Z = 4; K3Cr11S18: a = 41.876(3) Å, b = 3.463(1) Å, c = 16.315(3) Å, β = 150.07(1)°, Z = 2; RbCr5Se8: a = 18.737(2) Å, b = 3.623(1) Å; c = 9.016(1) Å, β = 104.65(1)°, Z = 2; CsCr5Se8: a = 18.795(2) Å, b = 3.637(1) Å, c = 9.104(1) Å, β = 104.52(1)°, Z = 2).We propose a structure classification from group-subgroup-relations.MAPLE calculations reveal that the reactions of the binary chalcogenides to yield the ternary compounds are exothermic in each case and are dependent on the chromium/alkali metal ratio in the ternary chalcogenides.
Notes:
Durch Umsetzungen der Alkalimetallcarbonate mit Chrom und dem entsprechenden Chalkogen in der Schmelze konnten die Verbindungen RbCr3S5, K3Cr11S18, RbCr5Se8 und CsCr5Se8 als gut ausgebildete Kristalle erhalten werden. Die Verbindungen kristallisieren monoklin im Raumgruppentyp C2/m (RbCr3S5: a = 19,372(3) Å, b = 3,498(1) Å, c = 12,119(2) Å, β = 122,78(1)°, Z = 4; K3Cr11S18: a = 41,876(3) Å, b = 3,463(1) Å, c = 16,315(3) Å, β = 150,07(1)°, Z = 2; RbCr5Se8: a = 18,737(2) Å, b = 3,623(1) Å; c = 9,016(1) Å, β = 104,65(1)°, Z = 2; CsCr5Se8: a = 18,795(2) Å, b = 3,637(1) Å, c = 9,104(1) Å, β = 104,52(1)°, Z = 2).Über Gruppe-Untergruppe-Beziehungen wird eine Struktursystematik vorgeschlagen.MAPLE-Rechnungen zeigen, daß die Reaktionen der binären Chalkogenide zu den ternären Verbindungen jeweils exotherm sind und vom Verhältnis Chrom/Alkalimetall in den ternären Chalkogeniden abhängen.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/zaac.19936190205
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