M. Wiebcke, J. Felsche
May 1, 2001
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0
Influential Citations
16
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Journal
Microporous and Mesoporous Materials
Abstract
Abstract A reinvestigation of the crystal structure of the tetraethylammonium silicate hydrate with the approximate chemical composition (C 8 H 20 N) 6 [Si 6 O 15 ] · 40.8H 2 O ( 1 ) is reported. The crystal structure of tetraethylammonium hydroxide nonahydrate, (C 8 H 20 N)OH · 9H 2 O ( 2 ), has been determined for the first time. The structure of 1 has been refined to much higher precision in the centrosymmetric space group P 1 (Z=2) with a considerable degree of disorder, compared to a previous structure analysis in the non-centrosymmetric space group P1 without disorder (Sov. Phys. Crystallogr. 29 (1984) 421). 1 may be considered as a host–guest compound, in which trigonal-prismatic double three-ring silicate anions and water molecules form a complicated hydrogen-bonded host structure. The organic guest cations reside in straight channels and very irregular, not completely closed cages. The [Si 6 O 15 ] 6− oligoanions are stabilized in a specific organic–water environment by O–H ⋯ O hydrogen bonds and electrostatic and van der Waals O ⋯ CH 3 and O ⋯ CH 2 ( N ) anion–cation interactions. The NEt + 4 cations occur as conformers of approximate 4 2m(D 2d ) and 4 (S 4 ) molecular symmetry, depending on the location around the oligoanion. 2 is the first representative of a polyhedral clathrate hydrate of the NEt + 4 cation. The novel host structure is built from hydrogen-bonded water molecules and hydroxide ions.