Structural, Magnetic, and Spectroscopic Comparative Studies on Four New Derivatives of DIMMAL (2-Di1H-2-imidazolylmethylmalonate): A Novel Generator of Multidimensional Networks

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• 作者：Hugo Nú ; ñ ; ez ; Lucí ; a Soto ; Juan Server-Carrió ; Julia Garcí ; a-Lozano ; Amparo Sancho ; Rafael Acerete ; and Emilio Escrivà
• 刊名：Inorganic Chemistry
• 出版年：2005
• 出版时间：June 27, 2005
• 年：2005
• 卷：44
• 期：13
• 页码：4644 - 4655
• 全文大小：876K
• 年卷期：v.44,no.13(June 27, 2005)
• ISSN：1520-510X

文摘

This paper reports the synthesis, structure solution, and magnetic characterization of four new DIMMAL-containingcompounds (H₂DIMMAL = 2-di1H-2-imidazolylmethylmalonic acid), H₂DIMMAL·H₂O (1), Na₂(DIMMAL)·5H₂O (2),[Cu(HDIMMAL)₂] (3), and [Cu₂(DIMMAL)₂(H₂O)₂]·2H₂O (4). Compound 1, containing two carboxylates and twoprotonated imidazole rings, adopts the dizwitterion configuration. These monohydrate MBBs pack together into a3D array driven, as in the other three cases herein reported, by a combination of multiple-path H-bonds andaromatic-aromatic interactions. Compound 2 consists of centrosymmetric Na⁺ tetramers in which four NaO₆ distortedoctahedra are interconnected by carboxylate and water bridges. Compound 3 consists of mononuclear[Cu(HDIMMAL)₂] units in which HDIMMAL^- acts as a tridentate ligand through two imidazole N atoms and thedeprotonated O from a carboxylate. Compound 4 consists of centrosymmetric cyclic dinuclear [Cu₂(DIMMAL)₂(H₂O)₂]·2H₂O units involving propionate-arm bridges. The building-block units described above, in each case, areinterconnected into 3D networks by multiple H-bonding paths and aromatic-aromatic interactions. The EPR spectraare indicative of an essentially d_x²-y² ground state for the copper(II) ions in 3 and 4 (CuN₄O₂ and CuN₂O₂O'chromophores, respectively). Magnetic susceptibility measurements in the range of 1.8-200 K for compound 4show weak antiferromagnetic exchange between the copper(II) ions (2J = -1.6(1) cm^-1). The effectiveness of thepropionate-arm bridges, involving C-C bonds, in propagating magnetic exchange between the copper(II) ions isdiscussed.