Two structural isomers, 3,6-bis(2-chloro­phenyl)-1,4-di­hydro-1,2,4,5-tetrazine, (I), and 3,5-bis(2-chloro­phenyl)-4-amino-1H-1,2,4-triazole, (II), both C₁₄H₁₀Cl₂N₄, form chain-like structures in the solid state, stabilized by N-HN and N-HCl hydrogen bonds. A contribution from weak interactions to the strong hydrogen-bond network is observed in both structures. The secondary graph sets for intermolecular hydrogen bonds [(11) for (I) and (12) for (II)] indicate the similarity between the networks.