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Dynamic Proton Exchange in the Hydrogen Dihydroxide Ion H 3 O 2 − of the Hydroxosodalite Hydrate [Na 4 (H 3 O 2 )] 2 [SiAlO 4 ] 6 : 1 H MAS NMR Spectroscopic Evidence
Author(s) -
Engelhardt Günter,
Sieger Peter,
Felsche Jürgen
Publication year - 1992
Publication title -
angewandte chemie international edition in english
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 0570-0833
DOI - 10.1002/anie.199212101
Subject(s) - sodalite , hydrate , chemistry , ion , ion exchange , proton , activation energy , hydrogen , spectroscopy , crystallography , infrared spectroscopy , inorganic chemistry , analytical chemistry (journal) , physics , catalysis , zeolite , organic chemistry , quantum mechanics , biochemistry , chromatography
The activation energy is only about 40 kJ mol −1 for the dynamic exchange between the central and the terminal H atoms in the H 3 O 2 −ion. This was shown by solid‐state NMR spectroscopy on the title compound, in which the H 3 O 2 −ions occur isolated in sodalite cages. Since the splitting of H 3 O 2 −into H 2 O and OH − requires an energy of approximately 100 kJ mol −1 , such a pathway for the exchange is less likely than the mechanism depicted in (a).