Temperature dependences of the saturated vapor pressure of tin (IV) complexes with polydentate ligands

The present paper is a continuation of the previously pursued studies of thermal properties of the Sn(IV) complexes with tridentate iminopyridine ligands. The study of thermal properties including temperature dependences of the saturated vapor pressure for Sn(IV) complexes with the tridentate iminopyridine ligands by differential scanning calorimetry (DSC) and the Knudsen effusion method leads to the use of the studied compounds as luminescent materials, as well as components for nonlinear optics. Coordination compounds of tin (IV) containing tridentate Schiff bases were chosen as objects of research: 2,4-di-tert-butyl-6-((phenyl (pyridin-2-yl)methylene)amino)phenolatotrichlorotin(IV) (1), 4-methyl-2-((phenyl (pyridin-2-yl)methylene)amino)phenolatotrichlorotin(IV) (2), 4-chloro-2-((phenyl (pyridin-2-yl)methylene)amino) phenolatotrichlorotin(IV) (3). These compounds were obtained by template synthesis from tin tetrachloride, various o-aminophenols, and α-carbonyl substituted pyridines; they contain an iminopyridine function and are capable of covalently binding to a metal by a phenolic group. Phase transitions of compounds 1-3 were studied by DSC in the temperature range 25-500 °C. For all studied complexes an endothermic transition correlated to melting was revealed. The melting points of the studied compounds were taken to be the temperature values corresponding to the onset of the transition, according to the standard Netzsch Software Proteus method: 300, 320 and 330 °C for 1-3, respectively. The temperature dependences of the saturated vapor pressure were obtained for the studied complexes, using the Knudsen effusion method with the weight recording of the amounts of sublimated substances. As a result of the experiments it was found that compounds 1-3 sublimated in the temperature ranges of 239-244, 228-260 and 226-256 °C, respectively. Thermodynamic parameters of sublimation processes were calculated.