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• 作者：Carlos Meseguer ; Silvia Titos-Padilla ; Mikko M. H盲nninen ; R. Navarrete ; A. J. Mota ; Marco Evangelisti ; Jos茅 Ruiz ; Enrique Colacio
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：November 17, 2014
• 年：2014
• 卷：53
• 期：22
• 页码：12092-12099
• 全文大小：449K
• ISSN：1520-510X

文摘

New types of linear tetranuclear Ln^III-Ni^II-Ni^II-Ln^III (Ln^III = Dy (1), Gd (2)) complexes have been prepared using the multidentate ligand N,N鈥?bis(3-methoxysalicylidene)-1,3-diaminobenzene, which has two sets of NO and OO鈥?coordination pockets that are able to selectively accommodate Ni^II and Ln^III ions, respectively. The X-ray structure analysis reveals that the Ni^II ions are bridged by phenylenediimine groups forming a 12-membered metallacycle in the central body of the complex, whereas the Ln^III ions are located at both sides of the metallacycle and linked to the Ni^II ions by diphenoxo bridging groups. Phenylenediimine and diphenoxo bridging groups transmit ferromagnetic exchange interactions between the two Ni^II ions and between the Ni^II and the Ln^III ions, respectively. Complex 1 shows slow relaxation of the magnetization at zero field and a thermal energy barrier U_eff = 7.4 K with H_DC = 1000 Oe, whereas complex 2 exhibits an S = 9 ground state and significant magnetocaloric effect (鈭捨?i>S_m = 18.5 J kg^鈥? K^鈥? at T = 3 K and 螖B = 5 T).