Synthesis, thermochemical and quantum chemical studies on antimony(III) and bismuth(III) complexes with 2,2′-bipyridine and 1,10-phenanthroline

Abstract A thermochemical study of [SbCl 3 (L)] and [BiBr 3 (L)] complexes, wherein L is 2,2′-bipyridine (bpy) or 1,10-phenanthroline (phen), was performed by calorimetric measurements in solution. The complexes were synthesized and characterized by elemental analysis, FTIR spectroscopy and thermal analysis. From the enthalpies of dissolution of the complexes, salts and ligands in combination with auxiliary thermodynamic data, some thermochemical parameters of the complexes were determined by use of thermochemical cycles. Theoretical study on the complexes was performed using M06-2X/def2-TZVPP method. Donor-acceptor bond energies were obtained taking into account reorganization energies of the fragments. Our findings suggest that both the reorganization energy of the acceptor metal trihalide MX 3 (113–136 kJ · mol −1 ) and the rigidity of the phen govern the dissociation energy of the complexes. The theoretical results indicated that the chemical stabilities of the complexes decreases in order [BiBr 3 (phen)] > [SbCl 3 (phen)] > [BiBr 3 (bpy)] > [SbCl 3 (bpy)], agreeing with the experimental enthalpies of coordination in solid state.