Supramolecular Spin-Crossover Iron Complexes Based on Imidazole-Imidazolate Hydrogen Bonds

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• 作者：Yukinari Sunatsuki ; Hiromi Ohta ; Masaaki Kojima ; Yuichi Ikuta ; Yoshiyuki Goto ; Naohide Matsumoto ; Seiichiro Iijima ; Haruo Akashi ; Sumio Kaizaki ; Franç ; oise Dahan ; and Jean-Pierre Tuchagues
• 刊名：Inorganic Chemistry
• 出版年：2004
• 出版时间：July 12, 2004
• 年：2004
• 卷：43
• 期：14
• 页码：4154 - 4171
• 全文大小：905K
• 年卷期：v.43,no.14(July 12, 2004)
• ISSN：1520-510X

文摘

The [Fe^II(H₃L)](BF₄)₂·3H₂O (1) complex was synthesized, where H₃L (tris{[2-{(imidazole-4-yl)methylidene}amino]ethyl}amine) is a tripodal ligand obtained by condensation of tris(2-aminoethyl)amine and 4-formylimidazole (fim)in a 1:3 molar ratio. Starting from 1, a series of complexes, [Fe^II(H_1.5L)](BF₄)_0.5 (2) (=[Fe^II(H₃L)][Fe^II(L)]BF₄), [Fe(H_1.5L)]BF₄ (3) (=[Fe^II(H₃L)][Fe^III(L)](BF₄)₂), [Fe^III(H₃L)](BF₄)₃·fim·H₂O (4), and [Fe^III(L)]·2.5H₂O (5), has beensynthesized and characterized. The single-crystal X-ray structure of each complex has been determined. The Fe^IIcompound, 2, and a mixed valence Fe^II-Fe^III compound, 3, involve formally hemi-deprotonated ligands, H_1.5L. Thestructure of 3 consists of a homochiral two-dimensional assembled sheet, arising from the intermolecular hydrogenbonds between [Fe^II(H₃L)]²⁺ and [Fe^III(L)]⁰ (3). All but 5 exhibit spin crossover between low-spin (LS) and high-spin(HS) states. This is a rare case where both Fe^II and Fe^III complexes containing the same ligand exhibit spin-crossover behavior. Magnetic susceptibility and Mössbauer studies showed that 3 has three accessible electronicstates: LS Fe^II-LS Fe^III, HS Fe^II-LS Fe^III, and HS Fe^II-HS Fe^III. Compounds 1-3 show the light-induced excitedspin-state trapping effect at the Fe^II sites upon irradiation with green light. The solution magnetic properties, electronicspectra, and electrochemical properties of 1, 4, and 5 were also studied.