Investigation of the correlations between (19)F and (1)H NMR signals for various mono- and di-substituted octafluoro[2.2]paracyclophanes.

A selection of mono- and pseudo ortho di-substituted octafluoro[2.2]paracyclophane derivatives were analyzed using (19)F-(1)H HOESY, (1)H COSY and (19)F COSY techniques. This resulted in the unambiguous assignment of the (19)F and (1)H NMR resonances, and also revealed interesting solvent effects and noteworthy coupling patterns for various J(HH), J(HF), and J(FF) interactions, including observable through bond (7)J(FF) and (8)J(FF) couplings. For the four mono-substituted derivatives, the assignments were achieved through the combination of (19)F-(1)H HOESY, (1)H COSY and (19)F COSY techniques. The C(2) symmetry of the six pseudo ortho di-substituted derivatives that were examined produced simplified spectra, and careful inspection of the characteristic (1)H coupling patterns led to the assignment of (1)H signals. Therefore only (19)F-(1)H HOESY experiments were required to complete the assignments for those molecules. Refinements and alternative strategies for previous protocols are presented for the molecules that were less responsive to nuclear Overhauser effect (nOe) experiments.