The 1H, 13C and 31P NMR spectra of EZ pairs of some phosphorus substituted alkenes

The olefins Ph₂P(X)CH?CHR X=lone pair, O, S, Ch₃I; R?Ch₃, ph, P(X)ph₂] have been prepared and their ¹H, ¹³C and ³¹P NMR spectra measured. trans ³JP(IV)C] (range 18.3–25.7 Hz) is greater than cis ³JP(IV)C] (range 6.9–11 Hz) but this relationship does not hold for P(III) compounds. In the ³¹P spectra the E isomer absorbs to higher field than the Z isomer for P(III) and P(IV) compounds. The ¹H data are in accord with previous results; average substituent shielding coefficients for ph₂P(X) substituted alkenes are reported.