| Abstract: | The carbon-13 NMR spectra of 16 aliphatic phosphorus compounds with -PCl2, -P(OCH3)2, -P(CH3)2 or -PS(CH3)2 groups were determined and interpreted on the basis of the usual α, β-deshielding and γ-shielding effects. The α-effects of all the groups were quite large (15 to 30 ppm), though the β-effects were small (0 to 3 ppm). The γ-effects were also small (0·2 to 1·6 ppm), but of significance in suggesting reduced steric compression relative to that found for methyl and most of the common organic functional groups. This may be attributed to the greater length of the C? P bond. The phosphorus-31 NMR spectra of these compounds also show the existence of interaction with γ-carbons by exhibiting small additive upfield shifts. |
