Two coordination modes around the Cu(II) cations in complexes with benzo[b]furancarboxylic acids

• Published in: Chemical physics letters 2013-02, Vol.559, p.41-45
• Main Authors: Drzewiecka, Aleksandra, Koziol, Anna E., Klepka, Marcin T., Wolska, Anna, Jimenez-Pulido, Sonia B., Lis, Tadeusz, Ostrowska, Kinga, Struga, Marta
• Format: Article
• Language: English
• ISSN: 0009-2614; 1873-4448
• DOI: 10.1016/j.cplett.2013.01.011

[Display omitted] ► Cu(II) complexes with three benzo[b]furancarboxylic acids are structurally investigated. ► Metal–ligand interactions are studied by X-ray absorption spectroscopy. ► Depending on the ligand, mononuclear and dinuclear Cu(II) complexes have been obtained. ► X-ray crystal structure analysis of dinuclear complex has been performed. ► For one of the complexes different coordination modes exist in crystal and powder form. Three Cu(II) complexes with derivatives of the benzo[b]furancarboxylic acid have been synthesized and characterized by the elemental and thermal analyses, and IR spectroscopy. The geometry of metal–ligand interaction for all compounds has been described using X-ray absorption spectroscopy and for one of them by X-ray crystallography. Two mononuclear Cu(II) complexes, with 7-acetyl-5-bromo-6-hydroxy-3-methylbenzo[b]furan-2-carboxylic and 6-acetyl-5-hydroxy-2-methylbenzo[b]furan-3-carboxylic acids, exhibit a tetra-fold coordination, CuO4. The Cu(II) cation in crystals with 7-acetyl-6-methoxy-3-methyl-benzo[b]furan-2-carboxylic acid is penta-coordinated; the bridging COO− groups and ethanol molecule stabilize the dinuclear center Cu2O10. The powdered form of this complex is based on the Cu2O8 units, indicating the absence of the ethanol molecules.