title: Bistable multifunctionality and switchable strong ferromagnetic-to-antiferromagnetic coupling in a one-dimensional rhodium(I)-semiquinonato complex.
abstract: We present a comprehensive study of the synthesis, heat capacity, crystal structures, UV-vis-NIR and mid-IR spectra, DFT calculations, and magnetic and electrical properties of a one-dimensional (1D) rhodium(I)-semiquinonato complex, [Rh(3,6-DBSQ-4,5-(MeO)2)(CO)2]∞ (3), where 3,6-DBSQ-4,5-(MeO)2(•-) represents 3,6-di-tert-butyl-4,5-dimethoxy-1,2-benzosemiquinonato radical anion. The compound 3 comprises neutral 1D chains of complex molecules stacked in a staggered arrangement with short Rh-Rh distances of 3.0796(4) and 3.1045(4) Å at 226 K and exhibits unprecedented bistable multifunctionality with respect to its magnetic and conductive properties in the temperature range of 228-207 K. The observed bistability results from the thermal hysteresis across a first-order phase transition, and the transition accompanies the exchange of the interchain C-H···O hydrogen-bond partners between the semiquinonato ligands. The strong overlaps of the complex molecules lead to unusually strong ferromagnetic interactions in the low-temperature (LT) phase. Furthermore, the magnetic interactions in the 1D chain drastically change from strongly ferromagnetic in the LT phase to antiferromagnetic in the room-temperature (RT) phase with hysteresis. In addition, the compound 3 exhibits long-range antiferromagnetic ordering between the ferromagnetic chains and spontaneous magnetization because of spin canting (canted antiferromagnetism) at a transition temperature T(N) of 14.2 K. The electrical conductivity of 3 at 300 K is 4.8 × 10(-4) S cm(-1), which is relatively high despite Rh not being in a mixed-valence state. The temperature dependence of electrical resistivity also exhibits a clear hysteresis across the first-order phase transition. Furthermore, the ferromagnetic LT phase can be easily stabilized up to RT by the application of a relatively weak applied pressure of 1.4 kbar, which reflects the bistable characteristics and demonstrates the simultaneous control of multifunctionality through external perturbation.
authors.affiliation: Department of Material Science and ‡Research Center for New Functional Materials, Graduate School of Material Science, University of Hyogo , 3-2-1 Kouto, Kamigori-cho, Ako-gun, Hyogo 678-1297, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Mitsumi
authors.forename: Takashi
authors.initials: T
authors.lastname: Nishitani
authors.forename: Shota
authors.initials: S
authors.lastname: Yamasaki
authors.forename: Nayuta
authors.initials: N
authors.lastname: Shimada
authors.forename: Yuuki
authors.initials: Y
authors.lastname: Komatsu
authors.forename: Koshiro
authors.initials: K
authors.lastname: Toriumi
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Kitagawa
authors.forename: Mitsutaka
authors.initials: M
authors.lastname: Okumura
authors.forename: Yuji
authors.initials: Y
authors.lastname: Miyazaki
authors.forename: Natalia
authors.initials: N
authors.lastname: Górska
authors.forename: Akira
authors.initials: A
authors.lastname: Inaba
authors.forename: Akinori
authors.initials: A
authors.lastname: Kanda
authors.forename: Noriaki
authors.initials: N
authors.lastname: Hanasaki