Determination of polyaminocarboxylate ligand denticity by 13C NMR paramagnetic line broadening
✍ Scribed by K. Popov; A. Vendilo; N. Djatlova
- Publisher
- John Wiley and Sons
- Year
- 1991
- Tongue
- English
- Weight
- 246 KB
- Volume
- 29
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
Abstract
The ^13^C NMR characteristics of sodium acetate and complexes of ethylenediaminetetraacetic acid (EDTA, H~4~edta) with La^3+^ and VO~2~^+^ in the presence of the paramagnetic relaxant [Gd(H~2~O)~n~ edta]^−^ are reported. The observed selective paramagnetic line broadening of the uncoordinated glycinate arms in [VO~2~edta]^3−^ permits an assignment of the ^13^C resonances and independent ligand denticity determination. For COO resonances the selectivity was found to be ca. 18. A large difference was also observed between the ^13^C transverse relaxation times for the uncoordinated COO groups of CH~3~COO^−^ and the coordinated COO groups of [La(H~2~O)~3~edta]^−^. The magnitude of the selectivity provides clear advantages in aiding the ^13^C NMR assignment and the establishment of the true denticity for the complexes of polydentate ligands.