Creation of Magnetic Ferroelectrics Based on Hydrogen-Bonded Benzosemiquinone Complexes

2014 Fiscal Year Final Research Report

• Project/Area Number: 24550162
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Functional materials chemistry
• Research Institution: University of Hyogo
• Principal Investigator: MITSUMI Minoru 兵庫県立大学, 物質理学研究科, 助教 (20295752)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: セミキノン錯体 / プロトン秩序ー無秩序転移 / プロトンダイナミクス / 固体高分解能NMR / 誘電性

Outline of Final Research Achievements

We have synthesized one-dimensional hydrogen-bonded rhodium(II)-η5-semiquinone complexes [Cp*Rh(η5-p-HQ-Me4)]X (X=PF6 (1), CF3SO3(2)) that exhibits a paraelectric-antiferroelectric second-order phase transition at 237.1 and 207.8 K, respectively. The 13C CP/MAS NMR spectra demonstrate that the proton is dynamically disordered in the RT phase. To maintain short-range protonic correlations, kink defects known as protonic solitons are expected to form topologically on the boundary of short-range order areas. The protonation/deprotonation of [Cp*Rh(η5-p-HQ-Me4)]+ led to hapticity changes of semiquinone ligand accompanied by reduction/oxidation by the π-bonded rhodium fragment, giving stable η6-hydroquinone and η4-benzoquinone complexes, respectively. Therefore, kink defects presumably consist of these stable η6- and η4-coordinated complexes. The generated protonic solitons migrate rapidly in the H-bonded chain through successive proton transfer coupled with electron transfer.

Free Research Field

錯体化学