Copper Coordination Polymers Based on Single-Chain or Sheet Structures Involving Dinuclear and Tetranuclear Copper(II) Units: Synthesis, Structures, and Magnetostructural Correlations

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• 作者：Santokh Singh Tandon ; Scott D. Bunge ; Douglas Motry ; Jos Snchez Costa ; Guillem Arom ; Jan Reedijk ; Laurence K. Thompson
• 刊名：Inorganic Chemistry
• 出版年：2009
• 出版时间：June 1, 2009
• 年：2009
• 卷：48
• 期：11
• 页码：4873-4881
• 全文大小：995K
• 年卷期：v.48,no.11(June 1, 2009)
• ISSN：1520-510X

文摘

Reactions between the potentially pentadentate (N₂O₃), trianionic double Schiff-base ligand 2,6-bis[[(2-hydroxyethyl)imino]methyl]-4-methylphenol (H₃L) and Cu(CH₃CO₂)₂ or Cu(ClO₄)₂, in the presence of NaN₃, give novel coordination polymers with chain {[Cu₂(H₂L)(N₃)₃]₂·H₂O}_n (1) or sheet [Cu₂(H₂L)(N₃)₃]_n (2) and [Cu₂(HL)(N₃)]_n[ClO₄]_n (3) structures, respectively. These clusters are comprised of repeating dinuclear units (1) or their dimers (2 and 3). In these compounds, H₃L acts as a tridentate (N₂O) monoanionic (1), tetradentate (ON₂O) monoanionic (2), or pentadentate (O₃N₂) dianionic (3) ligand. Compound [Cu₂(HL)(N₃)₂(H₂O)]·0.5CH₃OH (4) formed from the reaction of Cu(CH₃CO₂)₂ with H₃L under reflux, which did not afford crystals suitable for X-ray studies. X-ray structure determinations have revealed that the basic building block in 1−3 comprises two copper centers bridged through one μ-phenolate O atom from H₂L⁻ or HL^2- and one μ-azido(N1,N1) ion. Compounds 1−3 unveil three different ways in which this Cu₂ basic unit may be organized in the crystalline phase at the supramolecular level through a variety of bridging interactions involving additional azide ligands or alkoxide groups from the side arms of the ligand H₃L. Bulk magnetization measurements have served to demonstrate that the magnetic interactions are completely dominated by the strong antiferromagnetic coupling occurring within the Cu₂ building block, with coupling constants ranging from 330 to 560 cm⁻¹ (in the H = −JS₁S₂ convention). These results together have been incorporated with data from the few related copper dimers reported exhibiting the same bridging pattern into a study aimed at extracting possible magnetostructural correlations within this Cu₂ unit. An earlier predicted correlation between J and the angle formed by the phenoxide bridge and the Cu₂ core has been identified for the first time.