Thermochemistry of TM(II) Complexes (TM=Ni, Cu and Zn) and Their Ligands from DFT Calculations

Complexes of three transition-metal (TM) cations, Ni(II), Cu(II) and Zn(II), with four different ligands, namely, the tetradentate bis(acetylacetone)ethylenediamine, H2acacen, and bis(salicylidene)ethylenediimine, H2salen, ligands and the bidentate glycine, Hgly, and 8-hydroxyquinoline, Hox, ligands have been studied by means of the density functional theory based B3LYP method and considering all-electron basis sets. The enthalpies of deprotonation and of bond dissociation, at T=298.15 K, of the ligands were calculated and the values are found to be in very good agreement with available experimental data. The calculations were further extended to the standard molar enthalpies of formation in the gas-phase, T = 298.15 K, for the metal complexes by using pertinent working reactions and previously determined experimental enthalpies of formation for key species. Very good agreement was obtained and new values are estimated for the TM(gly)2 and Zn(acacen) complexes. In the cases of the Ni(gly)2 and Cu(gly)2 compounds, new values are suggested.