Synthesis under self-controlled reaction conditions: Reaction of tetraamminezinc(II) chloride with 3,5-dimethyl-1-thiocarboxamide pyrazole

The trinuclear [Zn3(Hdmpz)2(dmpz)4(NCS)2] complex (Hdmpz: 3,5-dimethylpyrazole) has been synthesized by the reaction of tetraamminezinc(II) chloride with 3,5-dimethyl-1-thiocarboxamidepyrazole. The ammonia evolving gradually from [Zn(NH3)4]Cl2 ensured a mild gradually increasing basic pH during the synthesis which caused a cleavage of the 1-N-substituent. Moreover, the changing pH controlled the pyrazolate anion–neutral ligand equilibrium, and in this way the formation of the precipitate complex. The structure of the complex was investigated by X-ray diffraction and quantum chemical computations. The complex was characterized in detail by FT-IR-spectroscopy and thermal analysis. The bonding interactions between Zn2+ and the ligands were analysed on the basis of the computed data.