Copper(II) complexes with pyridine-2,6-dicarboxylic acid from the oxidation of copper(I) iodide

Abstract

Via an oxidation reaction of Cu(I) iodide with pyridine-2,6-dicarboxylic acid (H₂L) in DMF three copper(II) complexes, [(CH₃)₂NH₂]₂[CuL₂] (1), K₂[CuL₂]∙H₂L∙H₂O (2) and [Cu(L)(H₂O)]_n (3), were synthesized and characterized. The structures of 1–3 were determined by single crystal X-ray diffraction studies. In-situ DMF decomposition produces dimethylamine base under solvothermal conditions and a proton transfer reaction takes place for the complex formation of 1. 3-D networks are stabilized in 1 and 2 via hydrogen bonds. Complex 3 is a 1-D coordination polymer with Cu-O semi-coordination bonds. Thermal decomposition of the complexes results in the corresponding metal oxides. Also, the electrochemical behavior of 1 was determined to be a metal-centered and diffusion-controlled, one-electron reduction process.

Keywords:

• Copper
• pyridine-2,6-dicarboxylic acid
• proton transfer
• dipicolinic acid
• cyclic voltammetry

Acknowledgements

Małgorzata Hołyńska acknowledges the help of Michael Marsch (support with X-ray diffraction studies).