Do nonmetallic superalkali cations exist?

- The existence of non-metallic superalkali cations is proposed in the present work.
- The positive fragmentation energies indicate the stabilities of the M2H2n+1+ cations.
- The M2H2n+1+ species exhibit low vertical electron affinities of 3.55-4.48 eV.
- The M2H2n+1+ cations are compared with the Li-based M2Li2k+1+ superalkali cations.