The Crystal Structure of KAlP₂O₇

Abstract

KAIP207 crystallizes as monoclinic crystals with a = 7. 308(8), b = 9.662(6), c = 8.025(4) A, = 106.69(7)", z = 4 and space group P2Jc. The structure was refined from 1394 observed reflections by fullmatrix least-squares method to a final R value of 0.032. The P2074-anion consists of a pair of cornersharing PO4 groups in a nearly staggered configuration. The mean bridging and terminal P-0 bond lengths are 1.607 and 1.509 A, respectively, and the P-0-P angle is 123.2". The anions lie in planes parallel to (001). The A1 ions are bonded to six oxygen atoms contributed by anions in three layers of P 2 0 7 groups. The average AI-0 bond length is 1.889 A. The potassium ion is coordinated to ten oxygen atoms lying within a spherical shell with inner and outer radii of 2.739 and 3.185 A. Can.

Structure de RbAlAs2O7

“…Le compos~ &udi~ poss6de une structure tr6s similaire aux pyrophosphates de type I isotypes de KA1P207 (Nam Ng & Calvo, 1973); CsMoP207, (Lii & Haushalter, 1987); KFeP207 (Riou, Labbe & Goreaud, 1988); KMo-P207 (Leclaire, Borel, Grandin & Raveau, 1989); RbMoP207 (Riou, Leclaire, Grandin & Raveau, 1989); CsVP207 (Wang & Lii, 1989); A1TiP207 (A ~ = K, Rb, Cs) (Wang & Hwu, 1991); (Rb, Cs)FeP207 (Millet & Mentzen, 1991); KVP207 (Benhamada, Grandin, Borel, Leclaire & Raveau, 1991). NaAIAs207 pr6sente des analogies structurales avec les pyrophosphates de type II isotypes ou semblables ~i NaFeP207-II (Gabelica-Robert, Goreaud, Labbe & Raveau, 1982;Moya-Pizarro, Salmon, Fournes, Le Flem, Wanklyn & Hagemuller, 1984): NaMoP207 (Leclaire, Borel, Grandin & Raveau, 1988); /3-NaTiP207 (Leclaire, Benmoussa, Borel, Grandin & Raveau, 1988); NaVP207 (Wang, Lii & Wang, 1989).…”

Crystal structure of tetraammonium diphosphate, (NH4)4P2O7 at 22 °C

“…On the other hand, the geometry of the diphosphate group is very much in keeping with that found in other diphosphate structures. P-0-P angles at the bridging oxygen range from 123 to 157' for struct~~res with nearly staggered ailion coilfigurations (8). The nearly eclipsed anion configuration shows a narrower range of 127 to 138' (8).…”

NaYP2O7

“…The compounds of type I exhibit the KA1P207 structure (Nam Ng & Calvo, 1973), whereas those of type II are isotypic with NaFeP207 (Gabrlica-Robert, Goreaud, Labb6 & Raveau, 1982). The lithium-containing compounds form the third family and adopt the LiFeP207 structure (Genkina, Maksimov, Timofeeva, Bykov & Mel'nikov, 1985;Riou, Nguyen, Benloucif & Raveau, 1990).…”