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Intermolecular interactions in AST zeolites through 14 N NMR and DFT calculations
Author(s) -
Dib Eddy,
Freire Mélanie,
Pralong Valérie,
Mineva Tzonka,
Alonso Bruno
Publication year - 2017
Publication title -
acta crystallographica section c
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 17
ISSN - 2053-2296
DOI - 10.1107/s2053229616017022
Subject(s) - intermolecular force , tetramethylammonium , chemistry , hydrogen bond , coupling constant , crystallography , density functional theory , cluster (spacecraft) , computational chemistry , molecule , organic chemistry , ion , physics , particle physics , computer science , programming language
The structure of the silica AST zeolites (octadecasil) synthesized in fluoride medium using tetramethylammonium (TMA) as the organic structure‐directing agent has been reinvestigated using 14 N NMR quadrupolar parameters and DFT calculations. The value of the experimental 14 N quadrupolar coupling constant ( C Q = 27 kHz) is larger than expected for a TMA cation possessing a high degree of motion. The analysis of a DFT‐optimized octadecasil cluster along with the comparison between measured and calculated 14 N NMR parameters demonstrate the presence of weak C—H…O hydrogen bonds between the TMA in the [4 6 6 12 ] cages and the silica skeleton. These intermolecular interactions can be related to the presence of Si…F tetrel bonds within the [4 6 ] cages. These new results provide additional information with regard to the formation mechanisms and structure of the octadecasil zeolites.