Transition metal complexes with pyrazole-based ligands. Part 8. Characterization and thermal decomposition of zinc“II” complexes with di- and trisubstituted pyrazoles

Abstract

We report the synthesis and the characterization “elemental analysis, FT-IR spectroscopy, thermal methods and molar conductivity measurements” of the mixed complexes of zinc with acetate and 3-amino-5-methylpyrazole, HL1, [Zn“OAc”2“HL1”2], or 3-amino-5-phenylpyrazole, HL2, [Zn“OAc”2“HL2”2], or 4-acetyl-3-amino-5-methylpyrazole, HL3, [Zn“OAc”“L3”“HL3”]2, with isothiocyanate and HL2, [Zn“SCN”2“HL2”2], or HL3, [Zn“SCN”2“HL3”2], and with nitrate, isothiocyanate and 3,5-dimethyl-1-carboxamidinepyrazole, HL4, [Zn“NO3”“NCS”“HL4”2]. The thermal decomposition of the complexes is generally continuous resulting zinc oxide as end product, except [Zn“OAc”“L3”“HL3”]2, in which case a well-defined intermediate was observed between 570-620 K. On the basis of the IR spectra and elemental analysis data of the intermediate a decomposition scheme is proposed.