Study of [2-(2’-pyridyl)imidazole] complexes to confirm two main characteristic thermoanalytical behaviors of transition metal complexes based on imidazole derivatives

Abstract

Imidazole derivative ligands are recognized as useful models for biomimetic complexes. Among the inorganic–organic hybrid complexes, those with derivatives of imidazole heterocyclic N-donor ligands are interesting for their framework. In previous studies of complexes with imidazole derivative ligands, our group reported two main thermally induced decomposition behaviors supporting two different systematic decomposition trends. In this work, one of these characteristic decomposition mechanisms was again found. The final goal of these serial studies is the possibility to provide, by the experimental evidences, a prediction model of thermal stability and decomposition typical behavior by comparing the structural characteristics of a precipitated complex. 2-(2’-pyridyl)imidazole complexes with transition metal ions of general formula M(PyrIm)2(H2O)2 (where M = Cu, Zn, Cd, Mn or Co) were synthesized, characterized and studied by thermoanalytical techniques coupled to mass spectrometry, to suggest their decomposition mechanism by evolved gas analysis (EGA-MS). Complexes also showed the interesting possibility to be precipitated with two methanol molecules in the structure and to replace methanol molecules with water molecules under controlled conditions.