## Hgh -resolutton 27Al NhlR spectra of polycrystalhne alumrnntes have been studled at 70 4 hfHz hlaglc-angle spummg was used to reduce quadrupole effects and dlpolar mtenctlon. The isotropic \*'Al chenuul shrfts depend mamly on the AI-O coordmatlon For Al-O tetrahedra stufts of 55 to 80 ppm were
Aluminium-27 Solid-State NMR Study of Aluminium Coordination Complexes of Alizarin
✍ Scribed by Patrick Soubayrol; Gilbert Dana; Pascal P. Man
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 637 KB
- Volume
- 34
- Category
- Article
- ISSN
- 0749-1581
No coin nor oath required. For personal study only.
✦ Synopsis
The structures of complexes obtained by the reaction of alizarin (C,,H,O,) and Al'+ in basic media depend upon the reaction solvent and the nature of the base. With aqueous or methanolic solutions of sodium hydroxide a binuclear complex [ AI,(p-OH),(C,,H,0,),(Na)4(H~O)4] was obtained, which is stable as the tetrahydrate and is observed even in the gas phase by electrospray mass spectrometry. With potassium hydroxide the monohydrate form is obtained. These two products are distinguishable by 27AI NMR in the solid state by means of their chemical shifts (+23.1 and 0.0 ppm) and their linewidths A V , , ~ (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,O molecules and dibenzene sandwich Na+) and 'open structure'.
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