Zinc(II) and nickel(II) complexes of 3,5-dimethyl-1-(pyridin-2-yl)-1H-pyrazole: relationship between fluorescence and crystal packing.

Two novel coordination com­plexes, namely, di­chlorido­[3,5-dimethyl-1-(pyri­din-2-yl-κN)-1H-pyrazole-κN2]zinc(II), [ZnCl2(C10H11N3)], 1, and aqua­chlorido­bis­[3,5-dimethyl-1-(pyri­din-2-yl-κN)-1H-pyrazole-κN2]nickel(II) chloride mono­hydrate, [NiCl(C10H11N3)(H2O)]Cl·H2O, 2, have been synthesized. The crystal structure analyses revealed that com­plexes 1 and 2 are mononuclear and have ZnN2Cl2 distorted tetra­hedral and NiN4OCl distorted octa­hedral structures, respectively. Complex 1 displays a dimer in the crystal structure, while com­plex 2 forms a chain along the [010] direction. The fluorescence properties of both com­plexes were also investigated. A search of the Cambridge Structural Data­base for other com­plexes of the ligand 3,5-dimethyl-1-(pyri­din-2-yl)-1H-pyrazole (L) shows that there exist different coordination polyhedra with different arrangements as monomers, dimers and polycyclic structures. Here it has also been demonstrated that there is a relationship between the crystal packing and the fluorescence properties of ZnII and CdII com­plexes of L.