American Chemical Society
cg100826c_si_002.cif (149.17 kB)

Polymorphism and Magnetism of (cis-Cyclohexane-1,4-diammonium)(Dicyclohexano[18]crown-6)2[Ni(dmit)2]2 Salts

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posted on 2010-11-03, 00:00 authored by Qiong Ye, Tomoyuki Akutagawa, Shin-ichiro Noro, Takayoshi Nakamura, Ren-Gen Xiong
Supramolecular cationic structures of (CHDA2+)(DCH[18]crown-6)2 were introduced into [Ni(dmit)2] salts (where CHDA2+, DCH[18]crown-6, and dmit2− represent cis-cyclohexane-1,4-diammonium, meso-dicyclohexano[18]crown-6, and 2-thioxo-1,3-dithiole-4,5-dithiolate, respectively). The crystal polymorphs of (CHDA2+)(DCH[18]crown-6)2[Ni(dmit)2]2 (crystals 1 and 2) within the same crystallization batch were classified in the space groups P21/n (1) and P1̅ (2). The N−H+∼O hydrogen-bonding interactions between the axial- and equatorial-ammonium moieties of the CHDA2+ cation and the oxygen atoms of DCH[18]crown-6 yielded a sandwich-type 1:2 adduct of the supramolecular cation in 1 and 2. Although the overall cationic structures in 1 and 2 resembled one another, the [Ni(dmit)2] anion arrangements were distinctively different from each other. The lateral [Ni(dmit)2] dimer along the short axis of the anion was observed in 1, whereas two types of [Ni(dmit)2] π-dimer existed independently in 2. The weak intermolecular interactions between the [Ni(dmit)2] anions in 1 was reflected by the temperature dependent magnetic susceptibility, which followed the Curie−Weiss model. For 2, two different magnetic exchange energies arising from the different strengths of the π-dimer units dominated the magnetic properties.