Synthesis, characterization, and calorimetric investigation of ternary lanthanide complexes with benzoic acid and 2-phenylimidazo[4,5- f]1,10-phenanthroline.

A series of solid ternary lanthanide complexes with the general formula Ln(BA)(PIP) (Ln = La-Lu, except Pm) were prepared with hydrated lanthanide chloride, benzoic acid (BA), and 2-phenylimidazo[4,5- f]1,10-phenanthroline (PIP). These obtained complexes were characterized by means of elemental analysis, EDTA volumetric analysis, IR spectroscopy, X-ray powder diffraction, and mass spectroscopy. The thermal decomposition mechanism of all complexes in the solid state was explored using TG-DTG techniques under dynamic flow of air atmosphere. Moreover, the constant-volume combustion energies, ∆ U, of the complexes were determined by a precise rotating-bomb calorimeter (RBC-type II) at 298.15 K. Their standard molar enthalpies of combustion, $$ \Delta _{\text{c}} H_{\text{m}}^{\uptheta} $$ , and standard molar enthalpies of formation, $$ \Delta_{\text{f}} H_{\text{m}}^{\uptheta} $$ , were calculated. [ABSTRACT FROM AUTHOR]