title: Conformational polymorph of o-aminoanilinium(dibenzo[18]crown-6) supramolecules in [Ni(dmit)2]- salts.
abstract: The supramolecular (HOPD(+))(DB[18]crown-6) cation, in which HOPD(+) and DB[18]crown-6 are o-aminoanilinium and dibenzo[18]crown-6, respectively, was introduced into [Ni(dmit)(2)](-) salts (dmit(2-) = 2-thioxo-1,3-dithiole-4,5-dithiolate). Conformational polymorphs were observed as tetragonal (HOPD(+))(DB[18]crown-6)[Ni(dmit)(2)](-) (1) and monoclinic (HOPD(+))(DB[18]crown-6)[Ni(dmit)(2)](-) (2). The ammonium group of HOPD(+) in salts 1 and 2 formed the N-H(+)O hydrogen bonds at the bottom and upper positions of V-shaped DB[18]crown-6, respectively, thereby producing a different supramolecular conformation. The [Ni(dmit)(2)](-) anion arrangements in salts 1 and 2 were 4(1)-helical pi stacking and a two-dimensional layer, respectively, depending on the conformation of the supramolecular cations. The magnetic behavior of salts 1 and 2 obeyed the Curie-Weiss law at room temperature with S = 1/2 spin on the [Ni(dmit)(2)](-) anion. However, the g value and line width in the electron resonance spectra of salt 1 showed a magnetic anomaly at 28 K, which was owing to antiferromagnetic ordering in the 4(1)-helical [Ni(dmit)(2)](-) pi stack. Large temperature- and frequency-dependent dielectric responses were observed for salt 2 at temperatures above 200 K, whereas no particular dielectric responses were observed in salt 1. The molecular motion of HOPD(+) within the cationic layer of salt 2 contributed to the dielectric response, and this was supported by ab initio calculations showing the potential-energy curve for pendulum motion and by the large thermal parameters in the X-ray crystal structure analysis. The fixed (HOPD(+))(DB[18]crown-6) arrangement in the crystal of salt 1 was consistent with the small dielectric response. The steric hindrance of the o-amino group of HOPD(+) in the supramolecular cation structure yielded the conformational polymorph with different dielectric and magnetic properties.
authors.affiliation: Research Institute for Electronic Science, Hokkaido University, N20W10 kita-ku, Sapporo 001-0020, Japan. takuta@es.hokudai.ac.jp
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Akutagawa
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Koshinaka
authors.forename: Qiong
authors.initials: Q
authors.lastname: Ye
authors.forename: Shin-ichiro
authors.initials: S
authors.lastname: Noro
authors.forename: Jun
authors.initials: J
authors.lastname: Kawamata
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yamaki
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Nakamura
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry*; D043844:Crown Ethers / Q000737:chemistry*; D003460:Crystallization; D046911:Macromolecular Substances / Q000737:chemistry; D008280:Magnetics; D008968:Molecular Conformation; D009532:Nickel / Q000737:chemistry
chemical_list: D000814:Aniline Compounds; D043844:Crown Ethers; D046911:Macromolecular Substances; C002564:dibenzo-18-crown-6; D009532:Nickel