Abstract Deuterium isotope effects on 13 C nuclear shielding, n ΔC (D), transmitted across a D-labelled nitrogen atom were investigated for a series of para-substituted benzanilides. The two two-bond isotope shifts, 2 ΔC (D) are perturbed essentially in a trough-bond manner by change of the contribution of mesomeric structures. The magnitudes of 2 Δ (C [DOUBLE BOND] O) and 2 Δ (C-1′) are found to be mutually interdependent as evidenced by the ...