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Aluminium‐27 Solid‐State NMR Study of Aluminium Coordination Complexes of Alizarin
Author(s) -
Soubayrol Patrick,
Dana Gilbert,
Man Pascal P.
Publication year - 1996
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/(sici)1097-458x(199608)34:8<638::aid-omr926>3.0.co;2-5
Subject(s) - chemistry , tetrahydrate , molecule , potassium hydroxide , chelation , hydroxide , sodium hydroxide , inorganic chemistry , aqueous solution , proton nmr , aluminium hydroxide , aluminium , crystallography , crystal structure , stereochemistry , organic chemistry
The structures of complexes obtained by the reaction of alizarin (C 14 H 8 O 4 ) and Al 3+ in basic media depend upon the reaction solvent and the nature of the base. With aqueous or methanolic solutions of sodium hydroxide abinuclear complex [Al 2 (μ‐OH) 2 (C 14 H 6 O 4 ) 4 (Na) 4 (H 2 O) 4 ] was obtained, which is stable as the tetrahydrate and isobserved even in the gas phase by electrospray mass spectrometry. With potassium hydroxide the monohydrate form is obtained. These two products are distinguishable by 27 Al NMR in the solid state by means of their chemical shifts (+23.1 and 0.0 ppm) and their linewidths Δν 1/2 (1200 and 4000 Hz). The chemical shifts of these binuclear complexes or similar derivatives are discussed in relation to possible chelation of the four molecules of water with alizarinate entities according to the bulk of the cation. The results are illustrated by two types of structure, named ‘closed structure’ (with strongly chelated H 2 O molecules and dibenzene sandwich Na + ) and ‘open structure’.