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Intermolecular dynamics and paramagnetic properties of ethylenediaminetetraacetate complexes with the yttrium subgroup rare earth elements using nuclear magnetic resonance
Author(s) -
Babailov Sergey P.
Publication year - 2012
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.3884
Subject(s) - chemistry , lanthanide , paramagnetism , yttrium , intermolecular force , ion , lanthanide contraction , chelation , nmr spectra database , nuclear magnetic resonance spectroscopy , coordination number , analytical chemistry (journal) , spectral line , inorganic chemistry , nuclear magnetic resonance , molecule , stereochemistry , physics , organic chemistry , chromatography , quantum mechanics , astronomy , oxide
1 H nuclear magnetic resonance (NMR) measurements are reported for the D 2 O solutions of [Ln 3+ (EDTA 4− )] − complexes, where EDTA 4− is ethylenediaminetetraacetate anion, Ln 3+ = Tb 3+ (I), Ho 3+ (II), Tm 3+ (III), Yb 3+ (IV) and Lu 3+ (V). Temperature dependencies of the 1 H NMR spectra of paramagnetic I–IV have been analyzed using the dynamic NMR methods. It is found that the activation free energies (Δ G ‡ 298 ) of the intermolecular EDTA ions exchange at [Ln 3+ (EDTA 4− )] − complexes are 60±3 (I), 66±3 (II), 69±3 (III) and 74±3 (IV) kJ/mol (at pD = 7). A monotonic increase of the free energy of chemical exchange processes along the series of lanthanide [Ln 3+ (EDTA 4− )] − complexes is probably related to the lanthanide contraction. The obtained results indicate that coordination compounds I–IV may be considered as thermometric NMR sensors and lanthanide paramagnetic probes for in situ temperature control in solution. Copyright © 2012 John Wiley & Sons, Ltd.