The detection of protonated cyanogen (NCCNH⁺) was reported in 2015 by Agúndez et al. Using the IRAM 30 m telescope as well as the Yebes 40 m telescope in Guadalajara Province (outside Madrid), NCCNH⁺ was detected toward TMC-1 and L483 via a pair of rotational lines. The detection has evidently not been confirmed to date. The rotational spectrum of NCCNH⁺ used in the detection was drawn from laboratory studies by Amano & Scappini in 1991 and by Gottlieb et al. in 2000. NCCNH⁺ was explored as a tracer of cyanogen, which does not have a dipole moment; by contrast isocyanogen (CNCN) has a dipole moment and was detected in 2018.

The cations detected in space fall into two categories: protonated atoms or closed-shell molecules like NCCNH⁺—including protonated He, Ar, water, H₂, HCl, CO at C, CO at O, carbon dioxide, N₂, cyanoacetylene, hydrogen cyanide, and formaldehyde—or ionized molecules like H₂O⁺, HF⁺, CO⁺, OH⁺, SH⁺, SO⁺, and CF⁺.