title: Molecular motion in pyridazinium/crown ether supramolecular cation salts of a nickel dithiolene complex.
abstract: Supramolecular cations formed by monoprotonated pyridazinium cations and cis-anti-cis-dicyclohexano[18]-crown-6 (DCH[18]-crown-6) or dibenzo[18]-crown-6 (DB[18]-crown-6) were introduced into [Ni(dmit)2]− salts (where dmit2− = 2-thione-1,3-dithiole-4,5-dithiolate). X-ray crystal structure analysis of (pyridazinium+)(DCH[18]-crown-6)[Ni(dmit)2]− (1) revealed a chair-type conformation of the DCH[18]-crown-6 moiety. A V-shaped conformation of the DB[18]-crown-6 moiety was observed in (pyridazinium+)(DB[18]-crown-6)2[Ni(dmit)2]−(H2O)2 (2). Nitrogen atoms in the pyridazinium cations interacted with the oxygen atoms of the DCH[18]-crown-6 and DB[18]-crown-6 through N–H+O hydrogen bonds, forming 1:1 and 1:2 supramolecular structures, respectively. Sufficient space for molecular motions of the pyridazinium cations, namely flip-flop and in-plane rotations, exists in salt 1. Disorder in nitrogen atoms was observed by X-ray analysis, indicating dynamic motion of the pyridazinium cation, namely flip-flop motion and in-plane motion. A potential energy calculation further supported the possibility of dynamic motion of cations in the crystal. By contrast, the flip-flop motion of the pyridazinium group in salt 2 is restricted by the two nearest-neighbouring DB[18]-crown-6 molecules. Weak antiferromagnetic intermolecular interactions between the [Ni(dmit)2]− anions in the two-dimensional layers of salt 1 were observed, resulting in alternating antiferromagnetic Heisenberg chain-type magnetic susceptibility. Quasi-one-dimensional intermolecular interactions between the [Ni(dmit)2]− anions were observed in salt 2, whose magnetic behaviour followed the Bonner–Fisher model.
authors.affiliation: Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0812, Japan. zunqi85@es.hokudai.ac.jp
authors.forename: Zun-qi
authors.initials: ZQ
authors.lastname: Liu
authors.forename: Kazuya
authors.initials: K
authors.lastname: Kubo
authors.forename: Li
authors.initials: L
authors.lastname: Lin
authors.forename: Norihisa
authors.initials: N
authors.lastname: Hoshino
authors.forename: Shin-ichiro
authors.initials: S
authors.lastname: Noro
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Akutagawa
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Nakamura
mesh_terms: D002412:Cations / Q000737:chemistry; D043844:Crown Ethers / Q000737:chemistry*; D006860:Hydrogen Bonding; D046911:Macromolecular Substances / Q000138:chemical synthesis / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D009532:Nickel / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D011724:Pyridazines / Q000737:chemistry*; D012492:Salts / Q000737:chemistry; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D002412:Cations; D043844:Crown Ethers; D046911:Macromolecular Substances; D009942:Organometallic Compounds; D011724:Pyridazines; D012492:Salts; D013438:Sulfhydryl Compounds; D009532:Nickel