- Organometallic ionic liquids from alkyloctamethylferrocenium cations: Thermal properties, crystal structures, and magnetic properties
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Alkyloctamethylferrocenium salts with the Tf2N anion ([Fe(C 5Me4CnH2n+1)(C5Me 4H)][Tf2N]; Tf2N = bis(trifluoromethanesulfonyl)amide) were prepared, and their ionic liquid properties, thermal properties, crystal structures, and magnetic properties were investigated. The melting points of the Tf2N salts were near room temperature, and decreased with increasing alkyl chain length up to n = 8 and then increased. The salts with PF6 and NO3 anions were also prepared. The melting points of the PF6 salts were higher than 100 °C. Most of these salts exhibited phase transitions in the solid state. The sum of the entropies of the melting and solid phase transitions was nearly independent of the alkyl chain length for salts with short alkyl chains, whereas those for salts with longer alkyl chains (n ≥ 10 for Tf2N salts, n ≥ 6 for PF6 salts) increased with increasing alkyl chain length. Crystal structure determinations revealed that the short chain salts form simple alternately packed structures of cations and anions in the solid state, and that the long chain salts form lamellar structures, in which the alkyl chains are aligned parallel between the layers. The effects of magnetic fields on the crystallization of the paramagnetic ionic liquids were investigated, and revealed that the Tf2N salts with n = 4 exhibited magnetic orientation when solidified under magnetic fields. The magnetic orientation was shown to be a bulk phenomenon, and the importance of the magnetic anisotropy of the crystal structure was suggested in comparison with the response of other Tf2N salts.
- Funasako, Yusuke,Inagaki, Takashi,Mochida, Tomoyuki,Sakurai, Toshihiro,Ohta, Hitoshi,Furukawa, Ko,Nakamura, Toshikazu
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- Thermal properties of alkyloctamethylferrocenium salts with TFSA and TCNE (TFSA = bis(trifluoromethylsulfonyl)amide and TCNE = tetracyanoethylene)
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Butyl- and hexyloctamethylferrocenium salts with bis(trifluoromethylsulfonyl)amide (TFSA) and tetracyanoethylene (TCNE) were prepared, and their thermal properties were investigated by differential scanning calorimetry (DSC) measurements. The TFSA salts were ionic liquids with melting points of 34.4 °C and 27.7 °C, respectively. The TCNE salts were prepared by annealing the mixture of alkyloctamethylferrocene and TCNE. These salts exhibited high melting points of 100.2 °C and 80.9 °C, respectively; they were thermally unstable at higher temperatures. A butyloctamethylferrocenium salt with PCNP (pentacyanopropenide), obtained by a reaction with TCNE under ambient conditions, was crystallographically characterized. The structure was severely disordered, consisting of alternately stacked cations and anions.
- Funasako, Yusuke,Abe, Ken-Ichi,Mochida, Tomoyuki
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