Mismatched molecular 1:1 complexes of C 10 F 8 with catenated chalcogen–nitrogen compounds C 6 H 5 –X–NSN–SiMe 3 (X=S, Se) were prepared and characterized by X-ray crystallography. The complexes provide examples of structurally non-rigid polyheteroatom molecules involved in non-covalent arene–polyfluoroarene π-stacking interactions. In going from homocrystals to the co-crystals, the molecular Z, E configuration of the catenated compounds changes from noticeably non-planar to perfectly planar, i.e. C 10 F 8 acts as “molecular iron”. On the other hand, C 10 H 8 does not produce complexes with C 6 F 5 –X–NSN–SiMe 3 (X=S, Se).