Unexpected Ferromagnetic Interaction in a New Tetranuclear Copper(II) Complex: Synthesis, Crystal Structure, Magnetic Properties, and Theoretical Studies

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• 作者：Matilde Fondo ; Ana M. Garcí ; a-Deibe ; Monstserrat Corbella ; Eliseo Ruiz ; Javier Tercero ; Jes&uacute ; s Sanmartí ; n ; and Manuel R. Bermejo
• 刊名：Inorganic Chemistry
• 出版年：2005
• 出版时间：July 11, 2005
• 年：2005
• 卷：44
• 期：14
• 页码：5011 - 5020
• 全文大小：232K
• 年卷期：v.44,no.14(July 11, 2005)
• ISSN：1520-510X

文摘

The new tetranuclear carbonate complex [Cu₂L)₂(CO₃)]·8H₂O (1·8H₂O) (H₃L = (2-(2-hydroxyphenyl)-1,3-bis[4-(2-hydroxyphenyl)-3-azabut-3-enyl]-1,3-imidazolidine) has been obtained by two different synthetic routes and fullycharacterized. Recrystallization of 1·8H₂O in methanol yields single crystals of {[(Cu₂L)₂(CO₃)]}₂·12H₂O (1·6H₂O),suitable for X-ray diffraction studies. The crystal structure of 1·6H₂O shows two crystallographically differenttetranuclear molecules in the asymmetric unit, 1a and 1b. Both molecules can be understood as self-assembledfrom two dinuclear [Cu₂L]⁺ cations, joined by a ₄-²:¹:¹ carbonate ligand. The copper atoms of eachcrystallographically different [(Cu₂L)₂(CO₃)] molecule present miscellaneous coordination polyhedra: in both 1aand 1b, two metal centers are in square pyramidal environments, one displays a square planar chromophore andthe other one has a geometry that can be considered as an intermediate between square pyramid and trigonalbipyramid. Magnetic studies reveal net intramolecular ferromagnetic coupling between the metal atoms. Densityfunctional calculations allow the assignment of the different magnetic coupling constants and explain the unexpectedferromagnetic behavior, because of the presence of an unusual NCN bridging moiety and countercomplementarityof the phenoxo (or carbonate) and NCN bridges.