Electric-field effects in nuclear magnetic resonance spectroscopy. Part III. 13C–1H spin–spin coupling constants

Abstract

If the linear electric-field dependence of the ¹³C–¹H spin–spin coupling constants in polar acetylacetonato-complexes is assumed to depend on the different electric field at both the ¹³C and ¹H nucleus, then effects at ¹H are shown to be predominant. Previous empirical equations giving the quantitative dependence of the coupling constant on electric field are revised, and shown to be consistent with theory. When electric-field effects are important, there is also a linear relationship between the ¹H and ¹³C shifts and the corresponding ¹³C–¹H coupling constant for both the methyl and methine groups.