Synthesis, Spectroscopic, and Structural Elucidation of Mixed-Ligand Coordination Complexes of Divalent and Trivalent Transition Metal Ions

Abstract

A series of novel mixed-ligand coordination complexes of Cu(II), Ni(II), Co(II), Cr(III), and Fe(III) ions were successfully synthesized using acetylacetone (acac) as the primary ligand and 1,10-phenanthroline (phen) as the secondary ligand. The complexes were synthesized in methanolic solution under reflux conditions and were characterized by elemental analysis (CHN), molar conductivity, Fourier-transform infrared (FT-IR) spectroscopy, electronic (UV-Vis) spectroscopy, and magnetic susceptibility measurements. Molar conductivity values confirmed the non-electrolytic nature of the complexes. FT-IR spectral data demonstrated coordination of the acetylacetonate anion via its oxygen atoms and 1,10-phenanthroline via its nitrogen atoms to the metal centers. Electronic spectral studies and magnetic moment measurements were used to propose the probable geometries around each metal ion. The data suggest an octahedral geometry for the Ni(II), Co(II), and Cr(III) complexes, a distorted octahedral geometry for the Cu(II) complex, and a high-spin octahedral geometry for the Fe(III) complex. The results confirm the successful formation of stable mixed-ligand complexes, with their spectroscopic and magnetic properties being significantly influenced by the identity of the central metal ion. This work provides a systematic comparison of the coordination behavior of divalent and trivalent transition metal ions within a similar mixed-ligand framework.