35Cl/ 37Cl isotope effects in 103Rh NMR of [RhCl n(H 2O) 6-n] 3-n complex anions in hydrochloric acid solution as a unique 'NMR finger-print' for unambiguous speciation
Date
2012
Authors
Geswindt T.E.
Gerber W.J.
Brand D.J.
Koch K.R.
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
A detailed analysis of the
35Cl/
37Cl isotope effects observed in the 19.11MHz
103Rh NMR resonances of [RhCl
n(H
2O)
6-n]
3-n complexes (n=3-6) in acidic solution at 292.1K, shows that the 'fine structure' of each
103Rh resonance can be understood in terms of the unique isotopologue and in certain instances the isotopomer distribution in each complex. These
35Cl/
37Cl isotope effects in the
103Rh NMR resonance of the [Rh
35/37Cl
6]
3- species manifest only as a result of the statistically expected
35Cl/
37Cl isotopologues, whereas for the aquated species such as for example [Rh
35/37Cl
5(H
2O)]
2-, cis-[Rh
35/37Cl
4(H
2O)
2]
- as well as the mer-[Rh
35/37Cl
3(H
2O)
3] complexes, additional fine-structure due to the various possible isotopomers within each class of isotopologues, is visible. Of interest is the possibility of the direct identification of stereoisomers cis-[RhCl
4(H
2O)
2]
-, trans-[RhCl
4(H
2O)
2]
-, fac-[RhCl
3(H
2O)
3] and mer-[RhCl
3(H
2O)
3] based on the
103Rh NMR line shape, other than on the basis of their very similar δ(
103Rh) chemical shift. The
103Rh NMR resonance structure thus serves as a novel and unique 'NMR-fingerprint' leading to the unambiguous assignment of [RhCl
n(H
2O)
6-n]
3-n complexes (n=3-6), without reliance on accurate δ(
103Rh) chemical shifts. © 2012 Elsevier B.V.
Description
Keywords
103Rh NMR, 35Cl/
37Cl isotope effects in [RhCl
n(H
2O)
6-n]
3-n complexes, Direct
103Rh NMR speciation, Isotopologues and isotopomers in NMR
Citation
Analytica Chimica Acta
730
93
98
730
93
98