A Quasi-Tetrahedral Cu4 Cluster and a Helical-Chain Copper(II) Complex with Single Syn-Anti Carboxylate Bridges: Crystal Structure and Magnetic Properties

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• 作者：Subrata Kumar Dey ; Bappaditya Bag ; K. M. Abdul Malik ; M. Salah El Fallah ; Joan Ribas ; and Samiran Mitra
• 刊名：Inorganic Chemistry
• 出版年：2003
• 出版时间：June 30, 2003
• 年：2003
• 卷：42
• 期：13
• 页码：4029 - 4035
• 全文大小：138K
• 年卷期：v.42,no.13(June 30, 2003)
• ISSN：1520-510X

文摘

A tridentate Schiff base carboxylate ligand, derived from the condensation of pyridine 2-carboxaldehyde with anthranilicacid, reacts with copper trifluoroacetate salt to give rise to the helical chain complex [Cu(C₁₃H₉N₂O₂)(F₃CCO₂)]_n (1)and with copper nitrate to give rise to the tetranuclear complex [{Cu₄(C₁₃H₉N₂O₂)₄(H₂O)₄}·3.5NO₃·0.5N₃] (2) withthe addition of azide salt. The structures of these complexes have been solved by X-ray crystallography. TheCu(II) ions are in a distorted square-pyramidal environment in complex 1. They are sequentially bridged by carboxylategroups in the syn-anti conformation, resulting in the formation of an infinite helix like chain along the crystallographicc-axis. The crystal structure of complex 2 consists of tetranuclear [Cu₄(L)₄(H₂O)₄]⁴⁺ (L = C₁₃H₉N₂O₂^-) cations andisolated NO₃^- and N₃^- anions in the ratio 1:3.5:0.5, respectively, involving bridging carboxylate groups in thesyn-anti conformation. For 1 the carboxylato-Cu(II) coordination is apical-basal, while for 2 it is basal-basal.From the magnetic susceptibility measurements the complex 1 is found to exhibit very weak antiferromagneticinteraction whereas a weak ferromagnetic coupling has been established for complex 2. The magnetic behaviorcan be satisfactorily explained on the basis of the structural data for these and related complexes.