Theoretical study, and infrared and Raman spectra of copper(II) chelated complex with dibenzoylmethane

Area of Science:

• Inorganic Chemistry
• Computational Chemistry
• Spectroscopy

Background:

• Previous studies on copper (II) dibenzoylmethane (Cu(dbm)2) show discrepancies in vibrational assignments and metal-ligand (M-L) bond strengths.
• There is a lack of theoretical structure, Raman spectrum, and full vibrational assignment for Cu(dbm)2 in existing literature.

Purpose of the Study:

• To investigate the effect of phenyl substitution on the stability and electron delocalization of Cu(dbm)2 compared to bis(acetylacetonate) copper (II) (Cu(acac)2).
• To provide a comprehensive theoretical and experimental analysis of the vibrational spectra and M-L bond strengths in Cu(dbm)2.

Main Methods:

• Density Functional Theory (DFT) at the B3LYP level and MP2 calculations with various basis sets.
• Natural Bond Orbital (NBO) and Atoms-in-Molecules (AIM) analyses.
• Interpretation of experimental solid-phase infrared and Raman spectra using calculated vibrational modes.

Main Results:

• Calculated geometries and vibrational results show good agreement with experimental data.
• Electron delocalization and M-L bond strength in Cu(dbm)2 are found to be higher than in Cu(acac)2.
• Charge transfer studies and the in-phase symmetric O-Cu-O stretching mode are identified as reliable indicators of M-L bond strength.

Conclusions:

• The study provides a detailed vibrational assignment and theoretical structure for Cu(dbm)2.
• Cu(dbm)2 exhibits greater stability and electron delocalization than Cu(acac)2 due to phenyl group substitution.
• The findings resolve previous discrepancies and offer a robust method for assessing M-L bond strength in similar complexes.