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Titel: Structural links beetween zeolite-type and clathrate hydrate-type materials synthesis and crystal structure of [NMe4]16[Si8O20][OH]8.116H2O
Verfasser: Wiebcke, Michael
Hoebbel, Dagobert
Sprache: Englisch
Erscheinungsjahr: 1992
Quelle: Journal of the Chemical Society / Dalton transactions. - 1992, 1, S. 2451-2455
SWD-Schlagwörter: Hydroxide
Fraktionierte Kristallisation
DDC-Sachgruppe: 540 Chemie
Dokumentart : Journalartikel
Kurzfassung: A novel crystalline tetramethylammonium silicate hydroxide polyhydrate has been obtained by fractional crystallization at room temperature from a highly alkaline aqueous NMe4OH-SiO2 solution. X-Ray single-crystal studies at 200 K revealed the trigonal crystal system, the unit-cell constants (hexagonal setting) a = 18.126(2) and c = 57.529(9) A°, the space group R3 and Z = 3 formula units of [NMe4]16[Si8O20][OH] 8·116H2O per unit cell. The crystal structure has been determined from 1416 unique Mo-Ka¯ data and refined to R = 0.104. The host-guest compound is of polyhedral clathrate type with a mixed three-dimensional, (mainly) four-connected tetrahedral network composed of oligomeric silicate anions [Si8O20]8-, OH- ions and H2O molecules linked via hydrogen bonds O-H?O. The silicate anions are each built up of eight SiO4 tetrahedra sharing corners to form a cube (double four-ring structure). Cationic guest species NMe4+ are enclosed in large polyhedral cavities [4668], [425865], [51264] and [425867] of the host structure; small [46] cages (i.e. the double-ring anions) and [4356] cages are unoccupied. Each silicate anion is the centre of a specific and probably very stable finite cluster [(NMe4)6(Si8O20)·24H 2O]2-. It is suggested that the polyhydrate may be taken as a crystalline model system for studies on the structures of aqueous tetramethylammonium silicate solutions.
Link zu diesem Datensatz: urn:nbn:de:bsz:291-scidok-19518
SciDok-Publikation: 22-Dez-2008
Fakultät: Sonstige Einrichtungen
Fachrichtung: SE - INM Leibniz-Institut für Neue Materialien
Fakultät / Institution:INM
SE - Sonstige Einrichtungen

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