Asymmetrical [Ni(dmit)2]- arrangements induced by (1R,2R)-cyclohexanediammonium-crown ether supramolecules.
Structurally flexible (1R,2R)-cyclohexanediammonium (CHDA(2+)) 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 (dmit(2-) = 2-thioxo-1,3-dithiole-4,5-dithiolate). The two ammonium moieties of CHDA(2+) interacted with the crown ethers to form open-mouth-shaped sandwich-type cationic structures of (CHDA(2+))(crown ethers)(2), that is, (CHDA(2+))([18]crown-6)(2)[Ni(dmit)(2)](2)(-)() (1), (CHDA(2+))(B[18]crown-6)(2)[Ni(dmit)(2)](2)(-)() (2), (CHDA(2+))(DB[18]crown-6)(2)[Ni(dmit)(2)](2)(-)() (3), and (CHDA(2+))(DCH[18]crown-6)(2)[Ni(dmit)(2)](2)(-)() (4). The chiral structure of CHDA(2+) induced asymmetrical [Ni(dmit)(2)](-) arrangements in the crystals. A large frequency and temperature dependence of the dielectric response was observed in (CHDA(2+))(B[18]crown-6)(2), due to the pendulum motion of the cyclohexane ring along the nitrogen-nitrogen direction of CHDA(2+). 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.
Ye
Qiong
Q
Research Institute for Electronic Science, Hokkaido University, Sapporo 001-0020, Japan. ries_yeqiong@es.hokudai.ac.jp
Akutagawa
Tomoyuki
T
Endo
Toru
T
Noro
Shin-ichiro
S
Nakamura
Takayoshi
T
Xiong
Ren-Gen
RG