The infrared spectrum of 15N12C12C14N, 15N13C12C15N, 14N13C12C14N, and 15N13C13C14N

► High resolution infrared spectra of monoisotopically substituted cyanogen. ► First observation of transitions forbidden for cyanogen species with D∞h symmetry. ► Vibrational and rotational term value constants are given for 14N13C12C14N, 15N12C12C14N, 15N13C12C15N, and 15N13C13C14N. ► Infrared spectra from 450 cm−1 to 3000 cm−1.