A 1D Cu(II) coordination polymer exhibiting ferromagnetic interactions and a mononuclear Cu(II) complex of substituted pyrazole carboxylic acids: Synthesis, characterization and crystal structure

Reaction of 2 equiv. amount of copper(II) nitrate hexahydrate with 1 equiv. of 5-methyl-1-pyridin-2-yl-1H-pyrazole-3-carboxylic acid (PyPzCA) in presence of triethyl amine base afforded a 1D coordination polymeric compound [Cu2(PyPzCA)2(H2O)3(NO3)]NO3·H2O (1). Whereas, the same reaction when repeated with 1-(4,6-dimethyl-pyrimidin-2-yl)-5-methyl-1H-pyrazole-3-carboxylic acid (PymPzCA) instead of PyPzCA, a mononuclear compound [Cu(PymPzCA)]·2H2O·NEt3 (2) is formed. Both the complexes are crystallographically characterized. In 1, both the copper atoms (Cu1 and Cu2) have distorted square pyramidal geometry with N2O3 chromophore while, in 2, the central copper atom has a distorted trigonal bipyramidal geometry with N4O chromophore. Complex 1, is a 1D coordination polymer where the metal centers being far apart and are involved in a weak ferromagnetic interaction which is quite unexpected.

A Cu(II) coordination polymeric helix of pyridyl-pyrazole derived carboxylic acid has been successfully synthesized and structurally characterized by elemental analysis, IR, UV–Vis and X-ray crystallography. The complex is a 1D coordination polymer where the metal centers being far apart are involved in a weak ferromagnetic interaction which is quite unexpected.Figure optionsDownload as PowerPoint slideHighlights
► Pyridyl/pyrimidyl-pyrazole derived carboxylic acids.
► 1D Cu(II) coordination polymer.
► Magnetic study.