Correlation of thermal and spectral properties of zinc(II) complexes of pyridinecarboxylic acids with their crystal structures

Three zinc(II) pyridinecarboxylate complexes, namely [Zn(nicot)2(H2O)4], [Zn(picol)2(H2O)2]·2H2O and [Zn(dipicolH)2]·3H2O, where nicot = nicotinate, picol = picolinate and dipicolH = hydrogenpicolinate were prepared and characterised by the methods of the thermal analysis (TG/DTG, DTA), infrared spectroscopy and elemental analysis. The structure of the complex [Zn(nicot)2(H2O)4] was studied by the single crystal XRD. The correlation of the thermal and spectral properties of the complexes with their structures is discussed in the study. The correlation of the spectral data with the structures leads to ambiguous results while the accord and coherence was found between thermal properties and structures of the complexes for both steps of the thermal decomposition (dehydratation and pyrolysis of organic ligand).