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Isomerization of Keggin Al 13 Ions Followed by Diffusion Rates
Author(s) -
Oliveri Anna F.,
Colla Christopher A.,
Perkins Cory K.,
Akhavantabib Noushin,
Callahan Joseph R.,
Pilgrim Corey D.,
Smart Scott E.,
Cheong Paul H.Y.,
Pan Long,
Casey William H.
Publication year - 2016
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201604640
Subject(s) - isomerization , chemistry , glycine , ion , proton nmr , inorganic chemistry , catalysis , stereochemistry , organic chemistry , amino acid , biochemistry
The solution chemistry of aluminum has long interested scientists due to its relevance to materials chemistry and geochemistry. The dynamic behavior of large aluminum–oxo‐hydroxo clusters, specifically [Al 13 O 4 (OH) 24 (H 2 O) 12 ] 7+ ( Al 13 ), is the focus of this paper. 27 Al NMR, 1 H NMR, and 1 H DOSY techniques were used to follow the isomerization of the ϵ‐Al 13 in the presence of glycine and Ca 2+ at 90 °C. Although the conversion of ϵ‐Al 13 to new clusters and/or Baker–Figgis–Keggin isomers has been studied previously, new 1 H NMR and 1 H DOSY analyses provided information about the role of glycine, the ligated intermediates, and the mechanism of isomerization. New 1 H NMR data suggest that glycine plays a critical role in the isomerization. Surprisingly, glycine does not bind to Al 30 clusters, which were previously proposed as an intermediate in the isomerization. Additionally, a highly symmetric tetrahedral signal ( δ =72 ppm) appeared during the isomerization process, which evidence suggests corresponds to the long‐sought α‐Al 13 isomer in solution.