Multifunctional One-Dimensional Rhodium(I)鈥揝emiquinonato Complex: Substituent Effects on Crystal Structures and Solid-State Properties

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• 作者：Minoru Mitsumi ; Shoji Ohtake ; Yuki Kakuno ; Yuuki Komatsu ; Yoshiki Ozawa ; Koshiro Toriumi ; Nobuhiro Yasuda ; Nobuaki Azuma ; Yuji Miyazaki
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：November 3, 2014
• 年：2014
• 卷：53
• 期：21
• 页码：11710-11720
• 全文大小：591K
• ISSN：1520-510X

文摘

Two new one-dimensional (1D) rhodium(I)鈥搒emiquinonato complexes formulated as [Rh(3,6-DBSQ-4,5-PDO)(CO)₂]_{鈭?/sub> (4; 3,6-DBSQ-4,5-PDO^{鈥⑩€?/sup> = 3,6-di-tert-butyl-4,5-(1,3-propanedioxy)-1,2-benzosemiquinonato) and [Rh(3,6-DBSQ-4,5-(N,N鈥?DEN))(CO)2]鈭?/sub> (5; 3,6-DBSQ-4,5-(N,N鈥?DEN)鈥⑩€?/sup> = 3,6-di-tert-butyl-4,5-(N,N鈥?diethylenediamine)-1,2-benzosemiquinonato) were synthesized to explore the nature of the unusual structural phase transition and magnetic and conductive properties recently reported for [Rh(3,6-DBSQ-4,5-(MeO)2)(CO)2]鈭?/sub> (3; 3,6-DBSQ-4,5-(MeO)2鈥⑩€?/sup> = 3,6-di-tert-butyl-4,5-dimethoxy-1,2-benzosemiquinonato). Their crystal structures and magnetic and conductive properties were investigated. Compounds 4 and 5 comprise neutral 1D chains of complex molecules stacked in a staggered arrangement with fairly short average Rh鈥揜h distances of 3.06 脜 for 4 and 3.10 脜 for 5. These distances are similar to those for 3 (3.09 脜); however, the molecules of 5 are strongly dimerized in the 1D chain. Compound 4 undergoes a first-order phase transition at Ttrs = 229.1 K, and its magnetic properties drastically change from antiferromagnetic coupling in the room-temperature (RT) phase to strong ferromagnetic coupling in the low-temperature (LT) phase. In addition, compound 4 exhibits a long-range ordering of net magnetic moments originating from the imperfect cancellation of antiferromagnetically coupled spins between the ferromagnetic 1D chains at TN = 10.9 K. Furthermore, this compound exhibits an interesting crossover from a semiconductor with a small activation energy (Ea = 31 meV) in the RT phase to a semiconductor with a large activation energy (Ea = 199 meV) in the LT phase. These behaviors are commonly observed for 3. Alternating current susceptibility measurements of 4, however, revealed a frequency-dependent phenomenon below 5.2 K, which was not observed for 3, thus indicating a slow spin relaxation process that possibly arises from the movements of domain walls. In contrast, compound 5, which possesses a strongly dimerized structure in its 1D chain, shows no sign of strong ferromagnetic interactions and is an insulator, with a resistivity greater than 7 脳 107 惟 cm.}}