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

Abstract

Abstract The olefins Ph 2 P(X)CHCHR [X=lone pair, O, S, Ch 3 I ; RCh 3 , ph, P(X)ph 2 ] have been prepared and their 1 H, 13 C and 31 P NMR spectra measured. trans 3 J [P(IV)C] (range 18.3–25.7 Hz) is greater than cis 3 J [P(IV)C] (range 6.9–11 Hz) but this relationship does not hold for P(III) compounds. In the 31 P spectra the E isomer absorbs to higher field than the Z isomer for P(III) and P(IV) compounds. The 1 H data are in accord with previous results; average substituent shielding coefficients for ph 2 P(X) substituted alkenes are reported.