- Crystal Structures and Phase Sequences of Metallocenium Salts with Fluorinated Anions: Effects of Molecular Size and Symmetry on Phase Transitions to Ionic Plastic Crystals
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Sandwich compounds often exhibit various phase transitions, including those to plastic phases. To elucidate the general features of the phase transitions in metallocenium salts, the thermal properties and crystal structures of [Fe(C5Me5)2]X ([1]X), [Co(C5Me5)2]X ([2]X), and [Fe(C5Me4H)2]X ([3]X) have been investigated, where the counter anions (X) are Tf2N (=(CF3SO2)2N?), OTf (=CF3SO3?), PF6, and BF4. The Tf2N salts commonly undergo phase transitions from an ordered phase at low temperatures to an anion-disordered phase, followed by a plastic phase and finally melt at high temperatures. All these salts exhibit a phase transition to a plastic phase, and the transition temperature generally decreases with decreasing cation size and increasing anion size. The crystal structures of these salts comprise an alternating arrangement of cations and anions. About half of these salts exhibit phase transitions at low temperatures, which are mostly correlated with the order–disorder of the anion.
- Mochida, Tomoyuki,Funasako, Yusuke,Ishida, Mai,Saruta, Shingo,Kosone, Takashi,Kitazawa, Takafumi
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p. 15725 - 15732
(2016/10/25)
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- The dramatic acceleration effect of imidazolium ionic liquids on electron transfer reactions
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Imidazolium ionic liquids (ILs) exhibited a dramatic acceleration effect on the electron transfer from metal complexes such as (C5Me 5)2Fe(ii) and (C5Me5) 2Co(ii) to the oxygen molecule; this acceleration effect can be ascribed to the stabilization of the oxygen radical anions by coordinating with the acidic C2-H of imidazolium ILs. The Royal Society of Chemistry.
- Choi, Doo Seong,Kim, Dong Hyun,Shin, Ueon Sang,Deshmukh, Ravindra R.,Lee, Sang-Gi,Song, Choong Eui
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p. 3467 - 3469
(2008/03/12)
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