Crystal structure and thermal analysis of new mononuclear nickel (II) complexes with NNN type pyrazolyl ligands and halids

Mononuclear Ni(II) complexes of Bis-2,6(pyrazolyl)pyridine(pp), 2(1-pyrazolyl)-6-(3,5-dimethyl-pyrazol-1-yl)pyridine(mpp) and bis-2,6(3,5-dimethyl-pyrazolyl-lyl)pyridine(dmpp) were prepared in MeOH:H 2 O mixtures. The complexes were characterized using elemental analysis, IR spectroscopy, X-ray diffraction and thermal analysis. The molecular structure of [Nidmpp(H 2 O) 2 Br]Br was evaluated and the Ni(II) ion was found to be in a distorted octahedral coordination environment. One of the halogen ions was found to coordinate the Ni(II) ion whereas the other ion does not coordinate and forms hydrogen bonds with the water molecules situated on the neighboring complex molecules, resulting in a supramolecular arrangement. Thermogravimetric results showed three coordinated water molecules in the pp and mpp complexes. Conductometric and potentiometric studies of the complexes showed 2 and 1 turning points, respectively.