Supramolecular cations formed by monoprotonated pyridazinium cations and cis-anti-cis-dicyclohexano-crown-6 (DCH-crown-6) or dibenzo-crown-6 (DB-crown-6) were introduced into [Ni(dmit)2]- salts (where dmit2- = 2-thione-1,3-dithiole-4,5-dithiolate). X-ray crystal structure analysis of (pyridazinium+)(DCH-crown-6)[Ni(dmit) 2]- (1) revealed a chair-type conformation of the DCH-crown-6 moiety. A V-shaped conformation of the DB-crown-6 moiety was observed in (pyridazinium+)(DB-crown-6)2[Ni(dmit) 2]-(H2O)2 (2). Nitrogen atoms in the pyridazinium cations interacted with the oxygen atoms of the DCH-crown-6 and DB-crown-6 through N-H+∼O hydrogen bonds, forming 1:1 and 1:2 supramolecular structures, respectively. Sufficient space for molecular motions of the pyridazinium cations, namely flip-flop and in-plane rotations, exists in salt 1. Disorder in nitrogen atoms was observed by X-ray analysis, indicating dynamic motion of the pyridazinium cation, namely flip-flop motion and in-plane motion. A potential energy calculation further supported the possibility of dynamic motion of cations in the crystal. By contrast, the flip-flop motion of the pyridazinium group in salt 2 is restricted by the two nearest-neighbouring DB-crown-6 molecules. Weak antiferromagnetic intermolecular interactions between the [Ni(dmit)2]- anions in the two-dimensional layers of salt 1 were observed, resulting in alternating antiferromagnetic Heisenberg chain-type magnetic susceptibility. Quasi-one-dimensional intermolecular interactions between the [Ni(dmit) 2]- anions were observed in salt 2, whose magnetic behaviour followed the Bonner-Fisher model.