The Use of Shift Reagents in NMR Studies of Chemical Exchange.
ILLINOIS UNIV URBANA NOYES CHEMICAL LAB
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It is shown that paramagnetic chemical shift reagents can be useful in the measurement of chemical exchange rates by nmr methods. The rare earth complexes Mfod3, with their higher solubility and relatively small line-broadening, were found to be best suited for the purpose. The internal rotation of amides was studied in solutions of the Eufod3 complex, which increases the N-methyl chemical shift several fold and thereby raises the coalescence temperature by as much as 50C. The chief drawback of the method is the relatively high temperature at which the shift reagents have to be used to avoid objectionable line-broadening. Author
- Physical Chemistry