Study of copper(II) thiophenecarboxylate complexes with nicotinamide
详细信息 查看全文
- 作者：Jan Moncol ; Vladim¨ªr Kuchtanin ; Petra Polakovi?ov¨¢ ; Jerzy Mrozi¨½ski ; Bo?ena Kali¨½ska ; Marian Koman ; Zde¨¾ka Pad¨§lkov¨¢ ; Peter Segl¡¯a ; Milan Meln¨ªk
- 关键词：Copper(II) ; Nicotinamide ; Crystal structure ; Hydrogen bonds ; Thiophenecarboxylate
- 刊名：Polyhedron
- 出版年：2012
- 出版时间：19 September, 2012
- 年：2012
- 卷：45
- 期：1
- 页码：94-102
- 全文大小：1218 K
文摘
The synthesis and characterization of [Cu(3-Me-2-tpc)2(nia)2] (1), [Cu(5-Me-2-tpc)2(nia)2] (2), [Cu(2-tpc)2(nia)2] (3) and [Cu(5-Me-2-tpc)2(nia)2(H2O)] (4) (where 2-tpc is 2-thiophenecarboxylate, 3-Me-2-tpc is 3-methyl-2-thiophenecarboxylate, 5-Me-2-tpc is 5-methyl-2-thiophenecarboxylate and nia is nicotinamide) are reported. The complexes under study were characterized by electronic, IR, EPR spectroscopy, magnetic susceptibility over the temperature range and X-ray structure analysis. The coordination arrangement around each copper(II) atom is a distorted tetragonal bipyramidal. The discrepancies between two Cu-O axial bond distances increases in the order: 0 ? (complex 1) < 0.050 ? (complex 3) < 0.209 ? (complex 2) < 0.516 ? (complex 4, Cu1) < 0.746 ? (complex 4, Cu2), indicating that in the same order a distortion of the respective tetragonal bipyramids increases. This is in a good agreement with the ligand field band position in their electronic spectra.
The complex molecules of all compounds are connected through H-bonds into supramolecular chains or frameworks. Spectral and magnetic behaviours are discussed with regard to X-ray parameters. Small negative value of Weiss constants confirm an existence of a very weak antiferromagnetic interaction between Cu(II) magnetic center in the crystal lattice.
The EPR parameters are typical for a tetragonal bipyramidal Cu(II) complexes. The gav values at r.t. are somewhat lower than those at 77 K.