Divalent Transition Metal Complexes of 2-(Pyridin-2-yl)imidazole: Evolved Gas Analysis Predicting Model to Provide Characteristic Coordination

Abstract

Previously published studies on imidazole derivative ligands suggested two main characteristic complex structures that are independent on the central metal ion. By the thermally induced decomposition behaviors, two different systematic decomposition trends were proposed. In this work, one of these characteristic decomposition mechanisms was again found for precipitated 2-(pyridin-2-yl)imidazole complexes. The final goal of these serial studies is to provide, by experimental evidences, a prediction model of thermal stability and typical decomposition behavior by comparing the structural characteristics of precipitated complexes. 2-(Pyridin-2-yl)imidazole complexes with transition metal ions of the general formula M(PyIm)2(H2O)2 (where M = Cu, Fe, Ni, Pd, Pt, Zn) were synthesized, characterized, and studied by thermoanalytical techniques coupled to mass spectrometry, to suggest their decomposition mechanism by evolved gas analysis (EGA-MS). As experimentally demonstrated in previous works, these complexes can be precipitated with two methanol molecules in the structure. By differential scanning calorimetry it was shown that methanol molecules can be replaced by water molecules under controlled conditions.