Mononuclear and binuclear copper(II) complexes with bis(2-imidazolyl)(bis(methoxycarbonyl)methylmethane) (BIBM), a tripodal bis(imidazole) based ligand. Synthesis, crystal structure and magnetic Characterization of [Cu(BIBM)₂](ClO₄)<

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• 作者：Hugo S&aacute ; nchez^a ; Juan Server-Carrió ; ^a ; Emilio Escrivà ; ^a ; ^{escriva@uv.es} ; Lucia Soto^a ; Julia Garcí ; a-Lozano^a ; Amparo Sancho^a ; Carmen Ramí ; rez de Arellano^b
• 关键词：3-D networks ; Bis(imidazolyl) ; Tripodal ligand ; Oxalate bridge ; Magneto&ndash ; structural correlations
• 刊名：Polyhedron
• 出版年：2013
• 出版时间：13 February, 2013
• 年：2013
• 卷：50
• 期：1
• 页码：383-389
• 全文大小：934 K

文摘

Two new Cu(II) complexes with bis(2-imidazolyl) (bis(methoxycarbonyl)methylmethane) (BIBM), a tridentate bis(imidazole) based ligand with the formula [Cu(BIBM)₂](ClO₄)₂ (1) and [{Cu(BIBM)(H₂O)}₂(¦Ì_1,2,3,4-C₂O₄)](C₄O₄)¡¤6H₂O (2) have been synthesized and characterized. Compound 1 shows mononuclear cationic [Cu(BIBM)₂]²⁺ units and perchlorate ions. The coordination around the Cu(II) ion shows a tetragonally-elongated octahedral geometry. The BIBM ligand acts as a k³-N,N¡¯,O tripodal ligand, through two imidazole N atoms and a weak Cu-O(carboxymethyl) axial interaction. In the crystal structure cations and anions connect through H-bonds generating linear chains. Linear chains assemble forming molecular layers through imidazole rings aromatic-aromatic interactions. The structure of compound 2 consists on centrosymmetric oxalate-bridged binuclear [Cu₂(BIBM)₂(OH₂)₂(¦Ì_1,2,3,4-C₂O₄)]²⁺ units, squarate dianions and water molecules in a 1:1:6 relation. The geometry around copper ions could be described as tetragonally elongated octahedrons of the 4+1+1¡ä type. In the structure, molecular building blocks (MBBs) are packed together by multiple-path H-bonding and ¦Ð-¦Ð stacking interactions, giving rise to the supramolecular 3D network. The molecular EPR spectra is indicative of an essentially ground state for copper(II) ions in both compounds. Magnetic susceptibility measurements of compound 2 show strong antiferromagnetic exchange between the copper(II) ions (J = ?325 cm^?1). The magnitude of the exchange interaction is discussed in relation to the structural features and compared with published magneto-structural data on similar oxalato-bridged copper(II) compounds.