Diversity in the 1/2 spin arrangement of [Ni(dmit)(2)](-) anions in divalent Ca2+ (crown ether) supramolecular cation salts

Calcium ion (Ca2+) and crown ethers, 12-crown-4, 15-crown-5, 1-aza-18-crown -6 (A18-crown-6) and 1,10-diaza-18-crown-6 (DA18-crown-6), were assembled i nto divalent supramolecular cation (SC2+) structures in the monovalent [Ni( dmit)(2)](-) salts (dmit(2-) =2-thioxo-1,3-dithiole-4,5-dithiolate), which regulate the arrangement of the [Ni(dmit)(2)](-) anions in the crystal. The divalent SC2+-[Ni(dmit)(2)](-) system showed a larger diversity of crystal structures compared with the monovalent SC+ system. Peculiar magnetic beha vior was observed depending on the arrangement of the S = 1/2 spins on the [Ni(dmit)(2)](-) anions. Single crystals of Ca2+ (12-crown-4)(2)[Ni(dmit)(2 )](2) (1) and Ca2+ (15-crown-5)(2)[Ni(dmit)(2)](2)(CH3CN)(0.7) (2) had a ty pical sandwich-type Ca2+ (crown ether), structure, which included the forma tion of pi-pi dimers and monomers of [Ni(dmit)(2)](-) anions in the crystal . The temperature-dependent magnetic susceptibility (chi (m)) of salt 1 sho wed a magnetic transition at 190 K, at which temperature the spins on each [Ni(dmit)(2)](-) dimer formed a singlet pair. On the other hand. the magnet ic behavior of salt 2 obeyed the Curie-Weiss law. The Ca2+ ions in the isos tructural single crystals of Ca2+ (A18-crown-6)[Ni(dmit)(2)](2)(CH3CN)(2) ( 3) and Ca2+ (DA18-crown-6)[Ni(dmit)(2)](2)(CH3CN)(2) (4) were completely in cluded into the 18-crown-6 cavity, and further interacted with two CH3CN mo lecules from the axial posit ion. The resultant Ca2+(18-crown-6)(CH3CN)(2) cations induced the formation of uniform zig-zag chains of the [Ni(dmit)(2) ](-) anions, the magnetic susceptibility of which were explained by a one-d imensional Heisenberg antiferromagnetic linear chain. The magnetism of thes e salts was discussed in terms of the intermolecular transfer integral t.