ISSN:
1572-8927
Keywords:
Hydrogen-1
;
carbon-13
;
nitrogen-15
;
NMR
;
lutetium(III)
;
isothiocyanate
;
complexation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract A direct, low-temperature hydrogen-1, carbon-13, and nitrogen-15 nuclear magnetic resonance study of lutetium(III)-isothiocyanate complex formation in aqueous solvent mixtures has been completed. At −100°C to −120°C in water-acetone-Freon mixtures, ligand exchange is slowed sufficiently to permit the observation of separate1H,13C, and15N NMR signals for coordinated and free water and isothiocyanate ions. In the13C and15N spectra of NCS−, resonance signals for five complexes are observed over the range of concentrations studied. The13C chemical shifts of complexed NCS− varied from −0.5 ppm to −3 ppm from that of free anion. For the same complexes, the15N chemical shifts from free anion were about −11 ppm to −15 ppm. The magnitude and sign of the15N chemical shifts identified the nitrogen atom as the binding site in NCS−. The concentration dependence of the13C and15N signal areas, and estimates of the fraction of anion bound at each NCS−:Lu3+ mole ratio, were consistent with the formation of [(H2O)5Lu(NCS)]2+ through [(H2O)Lu(NCS)5]2−. Although proton and/or ligand exchange and the resulting bulk-coordinated signal overlap prevented accurate hydration number measurements, a good qualitative correlation of the water1H NMR spectral results with those of13C and15N was possible.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00972922
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