13 C, 13 C coupling constants of isotopically perturbed molecular systems: Cyclohexane, benzene

13 C, 13 C coupling constants in benzene and cyclohexane were measured using monodeuteriated derivatives where 13 C, 13 C two‐spin subsystems become slightly non‐equivalent (benzene, 1 J = 55.88, 2 J = 2.46, 3 J = 10.04; cyclohexane, 1 J = 33.10, 2 J = 2.12, = 3 J 2.05; all couplings in hertz within the error limits of 0.01 Hz). 12 C/ 13 C isotope effects for the 13 C chemical shifts were found to be non‐additive.