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.
J Am Chem Soc. 2014 May 14;136(19):7026-37. doi: 10.1021/ja5017014. Epub 2014 May 2.
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.
我们对一维（1D）铑（I）-半醌配合物[Rh(3,6-DBSQ-4,5-(MeO)2)(CO)2]∞（3）的合成、热容、晶体结构、紫外可见近红外和中红外光谱、DFT 计算、磁学和电学性质进行了全面研究，其中 3,6-DBSQ-4,5-(MeO)2(•-)表示 3,6-二叔丁基-4,5-二甲氧基-1,2-苯半醌自由基阴离子。该化合物 3 由堆叠在交错排列中的中性 1D 链组成，在 226 K 时，相邻 Rh-Rh 距离为 3.0796(4)和 3.1045(4)Å，表现出前所未有的磁和电性质的双稳多功能性，其温度范围为 228-207 K。观察到的双稳性是由于一级相变的热滞后引起的，相变伴随着半醌配体之间的链间 C-H···O 氢键供体和受体的交换。强重叠的配合物分子导致低温（LT）相下异常强的铁磁相互作用。此外，在低温（LT）相，1D 链中的磁相互作用从强铁磁变为室温（RT）相的反铁磁，具有磁滞。此外，由于在 14.2 K 的转变温度 T(N)下自旋倾斜（倾斜反铁磁），化合物 3 表现出铁磁链之间的长程反铁磁有序和自发磁化。在 300 K 时，3 的电导率为 4.8×10(-4)S cm(-1)，尽管 Rh 没有处于混合价态，但相对较高。电阻率的温度依赖性也在一级相变处表现出明显的磁滞。此外，通过施加相对较弱的 1.4 kbar 外加压力，很容易将铁磁低温（LT）相稳定到室温（RT），这反映了双稳特性，并通过外部干扰同时控制多功能性。
