The nuclear magnetic resonance spectrum (1H and19F) of 1,2,3,5hyphen;tetrafluorobenzene is described. All coupling constants are obtained by subspectral analysis applicable to an AAprime;XXprime;MR system. A perturbation treatment for the AAprime;XXprime;MY case is outlined and illustrated by the R(Y) part of the spectra of 1,2,3,5hyphen;tetrafluorobenzene and pentafluorobenzene. The chemical shifts and the magnitude of coupling constants agree with values obtained for similar molecules. Also the result that the sign ofJHForthois opposite to that ofJHFparais in accord with earlier findings. It is emphasized that HF and FF coupling constants follow a monotonic sequence fromJ orthothroughJ metatoJ para.
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