Spectroscopic and Theoretical Studies of a New Cerium (III) Complex with 3,3′‐(ortho‐Pyridinomethylene)di‐[4‐hydroxycoumarin

Abstract

A new cerium (III) complex with 3,3′‐(ortho‐pyridinomethylene)di‐[4‐hydroxycoumarin] (o‐PyDC) was synthesized and characterized by various spectroscopic methods: mass spectrometry, 1H NMR, 13C NMR, IR, and Raman spectroscopy. The experimental IR and Raman spectra of o‐PyDC were assigned to the corresponding normal modes on the basis of density functional theory calculations at B3LYP/6‐31G(d) optimized geometry. The NMR, Raman, and IR spectra of the Ce(III) complex were interpreted on the basis of comparison with those of the free ligand. The vibrational analysis and the NMR data give evidence that in the Ce(III) complex, the ligand coordinates with the metal ion through both the deprotonated hydroxyl groups and through the carbonyl groups. The spectroscopic data indicates that the pyridine nitrogen is also involved in coordination with Ce(III). Density functional calculations of a complex fragment structure were performed to elucidate further the binding mode of o‐PyDC to Ce(III) and to explain the NMR and vibrational spectroscopic results.