Transition metal complexes with pyrazole based ligands, part 27: Structural and thermal characterization of cobalt(II) halide and pseudohalide complexes with 4-acetyl-3-amino-5-methylpyrazole

Abstract

The crystal and molecular structures of four tetrahedral structurally similar [Co(aamp) 2 X 2 ] complexes (aamp = 4-acetyl-3-amino-5-methylpyrazole, X = Cl, Br, I and NCS) were determined by X-ray diffraction analysis and are discussed in detail. It was found that the different capacity of the ligand X (NCS vs. Cl, Br, I) for the formation of non-bonding contacts influence the mode of molecular association in the solid state. The complexes were characterized by UV-Vis spectroscopy. The first step of the thermal decomposition of the compounds was checked and is discussed in the view of the IR spectrum of the intermediate isolated from [Co(aamp) 2 Br 2 ] by the quasi-isothermal technique.