Synthesis, crystal structures and spectral properties of cobalt(II) complexes:: [CoL(N3)]•ClO4 and CoL(N3)2 [L = tris((3,5-dimethylpyrazol-1-yl)methyl)amine]

Two monomeric cobalt(II) complexes, [CoL(N-3)] . ClO4 (1) and CoL(N-3)(2) (2), where L is tris( (3,5-dimethylparazol-1-yl)methyl)amine, were synthesized and their crystal structures were determined by X-ray diffraction technique. Complex 1 is five coordinated with one azide nitrogen atom and four nitrogen atoms of the tris( (3,5-dimethylpyrazol-1-yl)methyl) amine ligand, and the metal center is in distorted trigonal bipyramidal environment. Complex 2 is six coordinated distorted octahedron with the two azide nitrogen atoms and four nitrogen donors of the tris( (3,5-dimethylpyrazol-1-yl)-methyl) amine ligand. The solution behaviors of the title complexes have been further investigated by UV-Vis, and H-1 NMR analysis. It is found that the formation of 1 and 2 depends on the molar ratio of the azide ion to metal salt and ligand. Complex I attached with one azide group is more stable and easy to generate than complex 2 incorporated with two azide groups, and the reasons were well discussed.