Vibrational assignment and structure of dibenzoylmethane. A density functional theoretical study.

Area of Science:

• Computational Chemistry
• Molecular Spectroscopy
• Organic Chemistry

Background:

• Dibenzoylmethane (DBM) is a beta-diketone with potential applications.
• Understanding its molecular structure and hydrogen bonding is crucial for predicting its properties.
• Previous studies have explored DBM's characteristics, but a comprehensive DFT analysis alongside experimental data is valuable.

Purpose of the Study:

• To investigate the molecular structure and vibrational frequencies of dibenzoylmethane (DBM) using DFT.
• To compare the properties of DBM with benzoylacetone (BA) and acetylacetone (AA).
• To elucidate the strength and implications of the intramolecular hydrogen bond in DBM.

Main Methods:

• Density Functional Theory (DFT) calculations at the B3LYP/6-311++G** level.
• Infrared (IR) and Raman spectroscopy for DBM and its deuterated analogue.
• Nuclear Magnetic Resonance (NMR) spectroscopy.
• Natural Bond Orbital (NBO) analysis and geometry optimization.

Main Results:

• DFT calculations accurately predicted the molecular structure and vibrational frequencies of DBM.
• The calculated hydrogen bond energy for DBM was found to be 16.15 kcal/mol, higher than that of AA.
• Experimental spectroscopic data (IR, Raman, NMR) corroborated the theoretical findings regarding hydrogen bond strength.
• NBO analysis confirmed the relative stability and strength of the hydrogen bond in DBM.

Conclusions:

• DBM possesses a stronger intramolecular hydrogen bond compared to BA and AA.
• The enhanced hydrogen bond contributes to the molecular stability of DBM.
• DFT calculations provide a reliable method for studying beta-diketone properties and hydrogen bonding.