ESTIMATION OF VICINAL PHOSPHORUS-31-HYDROGEN AND NITROGEN-14-HYDROGEN SPIN-SPIN COUPLING CONSTANTS IN SINGLE CONFORMERS

The magnitudes of the various vicinal constants in a disubstituted ethane, XCH2CH2Y, vary linearly with each other, provided the changes are caused only by changes in rotamer population. The phenomenon is illustrated in detail with the example of ClCH2CH2PSCl2. Using appropriate values for the 3JHH constants, estimates of 3JPHgauche and 3JPHtrans for this compound are obtained. Similar treatments are presented briefly for the compounds (CH3)3CCH2CH2N→ =C and H2C=CHCH2N→=C; the analysis of the spectrum of vinyl isocyanide is given. The values obtained from these measurements, combined with those obtained from the literature, support the hypothesis that 3JPH and 3JNH coupling constants show a dependence on dihedral angle similar to that of 3JHH.