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Complexes of aluminium with aminopolycarboxylic acids: 27 Al NMR and potentiometric studies
Author(s) -
Iyer R. K.,
Karweer S. B.,
Jain V. K.
Publication year - 1989
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260270406
Subject(s) - chemistry , potentiometric titration , denticity , protonation , nuclear magnetic resonance spectroscopy , octahedron , ligand (biochemistry) , hydrolysis , inorganic chemistry , crystallography , ion , stereochemistry , organic chemistry , crystal structure , biochemistry , receptor
The reactions of Al 3+ ion with a series of aminopolycarboxylic acids containing coordinating sites (denticity, n ) ranging from 3 to 8 were studied by potentiometric and 27 AI NMR methods. Hydrolysis constants of the complexes were determined by potentiometry. The 27 Al { 1 H} NMR data indicate a nearly linear relationship between the 27 Al chemical shift of the normal complex and denticity of the ligand up to n = 6. Hydroxo complexes form in all systems, and at high pH ( ca. 10) aluminate forms. Protonated complexes were formed in some cases. Diprotonated complexes of EDTA and PDTA have been identified by 27 Al NMR spectroscopy. Maximum deshielding of the 27 Al resonance was observed for the octahedral [Al(EDTA)] − complex. The Al‐NTA complex appears to be the most symmetric of the complexes.