Asymmetrical [Ni(dmit)₂]⁻ Arrangements Induced by (1<i>R</i>,2<i>R</i>)-Cyclohexanediammonium - Crown Ether Supramolecules

Structurally flexible (1R,2R)-cyclohexanediammonium (CHDA2+) dication formed hydrogen-bonding supramolecules with [18]crown-6, benzo[18]crown-6 (B[18]crown-6), dibenzo[18]crown-6 (DB[18]crown-6), and dicyclohexano[18]crown-6 (DCH[18]crown-6) in [Ni(dmit)2]− salts (dmit2− = 2-thioxo-1,3-dithiole-4,5-dithiolate). The two ammonium moieties of CHDA2+ interacted with the crown ethers to form open-mouth-shaped sandwich-type cationic structures of (CHDA2+)(crown ethers)2, that is, (CHDA2+)([18]crown-6)2[Ni(dmit)2]2− (1), (CHDA2+)(B[18]crown-6)2[Ni(dmit)2]2− (2), (CHDA2+)(DB[18]crown-6)2[Ni(dmit)2]2− (3), and (CHDA2+)(DCH[18]crown-6)2[Ni(dmit)2]2− (4). The chiral structure of CHDA2+ induced asymmetrical [Ni(dmit)2]− arrangements in the crystals. A large frequency and temperature dependence of the dielectric response was observed in (CHDA2+)(B[18]crown-6)2, due to the pendulum motion of the cyclohexane ring along the nitrogen−nitrogen direction of CHDA2+. Since the inversion center of the [Ni(dmit)2]− arrangements was lost in the unit cell due to the chiral space group, the salts 1−4 showed rather complicated magnetic behaviors. The temperature-dependent magnetic properties of salts 3 and 4 were explained by the sum of the Curie−Weiss and singlet−triplet thermal excitation models, with positive (ferromagnetic) and negative (antiferromagnetic) magnetic exchange energies, respectively.