Synthesis and characterization of two temperature-dependent copper(II) complexes based on 2,6-dimethylpyridine-3,5-dicarboxylate

Two temperature-dependent Cu(II) compounds, [Cu(mpdaH)2(H2O)4] center dot 4H2O (1) and [Cu(mpdaH)2]n (2) (H2mpda = 2,6-dimethylpyridine-3,5-dicarboxylic acid), have been synthesized under hydrothermal conditions and characterized by X-ray single crystal diffraction, elemental analysis, thermogravimetric analyses, and IR spectra. The structure at room temperature confirms that 1 is mononuclear with the octahedral coordination geometry. However, on warming to 120 degrees C the same reaction gives 2, in which copper(II) has square planar coordination and is further bridged by mpdaH- ligands to form extended 2-D layers with parallelogram-like (4,4) topology. Furthermore, in both complexes, through - stacking and hydrogen bonding interactions, 3-D supramolecular networks are assembled.