ISSN:
0044-2313
Keywords:
K6[Al2O6], Rb6[Al2O6]
;
preparation
;
crystal structure
;
MAPLE
;
CHARDI
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Description / Table of Contents:
Preparation of Crystal Structure of K6[Al2O6] and Rb6[Al2O6]Colourless single crystals of K6[Al2O6] have been prepared from intimate mixtures of KAlO2 and K2O (550°C, 90 d). The structure determination from four-circle diffractometer data (MoKα, 742 Io(hkl), R = 2.2%, Rw = 2.1%) confirms the space group C2/m with Z = 2; a = 698.25 pm, b = 1 103.54 pm, c = 646.49 pm, β = 102.49°.Colourless single crystals of hitherto unknown Rb6[Al2O6] have been prepared from intimate mixtures of RbAlO2 and Rb2O (520°C, 120 d). The structure determination from four-circle diffractometer data (MoKα, 1 240 Io(hkl)) results in the residual values R = 7.2%, Rw = 4.9%; space group C2/m; a = 725.92 pm, b = 1 143.33 pm, c = 678.06 pm, β = 104.05°; Z = 2.K6[Al2O6] and Rb6[Al2O6] are isostructural with K6[Fe2O6]. A characteristic structure unit is the anion [Al2O6]6- consisting of two edge-sharing [AlO4] tetrahedra.Effective Coordination Numbers (ECoN), Mean Fictive Ionic Radii (MEFIR), the Madelung Part of Lattice Energy (MAPLE) and the Charge Distribution (CHARDI) are calculated and discussed.
Notes:
Farblose Einkristalle von K6[Al2O6] wurden aus innigen Gemengen von KAlO2 und K2O erhalten (550°C, 90 d). Die Strukturaufklärung (Vierkreisdiffraktometer, MoKα, 742 Io(hkl), R = 2,2%, Rw = 2,1%) bestätigt die Raumgruppe C2/m mit Z = 2; a = 698,25 pm, b = 1 103,54 pm, c = 646,49 pm, β = 102,49°.Analog erhielten wir erstmals Rb6[Al2O6] aus RbAlO2 und Rb2O in Form farbloser Einkristalle (520°C, 120 d). Die Strukturaufklärung (Vierkreisdiffraktometer, MoKα, 1 240 Io(hkl)) ergab in C2/m die Residualwerte R = 7,2%, Rw = 4,9%; a = 725,92 pm, b = 1 143,33 pm, c = 678,06 pm, β = 104,05°.K6[Al2O6] und Rb6[Al2O6] sind mit K6[Fe2O6] isotyp; charakteristische Strukturelemente sind die Anionen [Al2O6]6-, die aus zwei kantenverknüpften [AlO4]-Tetraedern bestehen.Effektive Koordinationszahlen (ECoN), Mittlere Fiktive Ionenradien (MEFIR), der Madelunganteil der Gitterenergie (MAPLE) sowie die Ladungsverteilung (CHARDI) werden berechnet und diskutiert.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/zaac.19946200522
