Isotope effect on the coupling constant1J(13C–H)

Abstract
The negative isotope effect on the coupling constant 1J(13C–H){ΔJ=(γH/γD)[1J(13C–D)]–1J(13C–H)} has been confirmed by INDO FP calculations of the 1J(13C–H) coupling constant in methane by varying one of the C–H distances.