Structural phase transition of magnetic [Ni(dmit)2]- salts induced by supramolecular cation structures of (M+)([12]crown- 4)2

Tomoyuki Akutagawa, Takeshi Motokizawa, Kazumasa Matsuura, Sadafumi Nishihara, Shin Ichiro Noro, Takayoshi Nakamura

研究成果: ジャーナルへの寄稿学術論文査読

37 被引用数 (Scopus)


Sandwich-type supramolecular cation structures of (M+)([12] crown-4)2 complexes (M+ = Li+, Na+, K+, and Rb+) were introduced as countercations to the [Ni(dmit)2]- anion, which bears an S = 1/2 spin, to form novel magnetic crystals (dmit2- = 2-thione-1,3-dithiole-4,5- dithiolate). The zigzag arrangement of Li+([12]crown-4)2 cations in Li+([12]crown-4)2[Ni(dmit)2] - salt induced weak intermolecular interactions of [Ni(dmit) 2]- dimers, whose magnetic spins were isolated from each other. The molecular arrangements of cations and anions in M+([12] crown-4)2[Ni(dmit)2]- salts (M+ = Na+, K+, and Rb+) were isostructural to each other. In the case of Na+([12]crown-4)2[Ni(dmit) 2]-, the space group C2/m changed to C2/c with a lowering in temperature from 298 to 100 K. This structural change occurred at 222.5 K as a first-order phase transition. The space group C2/m (T = 298 K) in the salt K+([12]crown-4)2[Ni(dmit)2]- also changed to C2/c (T = 100 K), which transition occurred at 270 K. Crystal structural analyses at 298 and 100 K revealed changes in both supramolecular cation conformation and [Ni(dmit)2]- anion arrangements. The transition from C2/m to C2/c crystals generated a dipole moment in the Na+([12]crown-4)2 and K+([12]crown-4) 2 structures, which were reconstructed to cancel the net dipole moment of the C2/c crystals. These cation transformations led to changes in intermolecular interactions between the [Ni(dmit)2]- anions via structural rearrangements. The crystal structure of C2/c was stabilized in Rb+([12]crown-4)2[Ni(dmit)2] - at 298 K. The [Ni(dmit)2]- configuration in these salts with the C2/c space group was a one-dimensional uniform chain, which showed the temperature-dependent magnetic susceptibility of a one-dimensional linear Heisenberg antiferromagnetic chain.

ジャーナルJournal of Physical Chemistry B
出版ステータス出版済み - 2006 3月 30


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