Determination of the rate of intramolecular exchange between two complex spin systems from the NMR spectra

Reversible 1,2-shifts of the ethyl group in the 9-ethyl-9, 10-dimethylphenanthrenonium ion lead to a reversible change of the ring hydrogen states (A′B′C′D′ ? A″B″C″D″). Line shape analysis for the determination of the exchange rate was performed for this case of intramolecular exchange between the two multi-spin systems. The calculations are based on density matrix formalism.