SYNTHESIS AND CRYSTAL STRUCTURE OF TETRAMETHYLAMMONIUM SODALITE

Tetramethylammonium sodalite, a synthetic species of composition (CH3)4NAlSi5O12, has been obtained in good yield under hydrothermal conditions in the absence of metal cations. Its crystal structure has been determined using accurate powder data since single crystals could not be grown. The structure seems to be body‐centered cubic with a = 8.975 Å but the true symmetry is non‐cubic (probable space group I4). Each cage of the aluminosilicate framework contains one tetramethylammonium ion. The organic cation does not conform to the cubic symmetry of the ideal framework. The methyl groups point to oxygen atoms of the framework, and the short methyl‐oxygen distances of 3.06 Å indicate strong CH … O interaction. The present results indicate beyond doubt that CH … O hydrogen bonding involving methyl groups can occur in silicates. This is of particular significance in zeolite chemistry and in the interpretation of interlayer distances in organic clay complexes. Copyright © 1969 Verlag GmbH & Co. KGaA, Weinheim