Molecular structure, vibrational spectroscopic studies and NBO analysis of the 3,5-dichlorophenylboronic acid molecule by the density functional method

Abstract

In this study, the Fourier-transform infrared (FT-IR) and FT-Raman spectra of 3,5-dichlorophenylboronicacid (3,5-dcpba) were recorded in the solid phase. The structural and spectroscopic analysis of the 3,5-dichlorophenylboronic was made by using density functional harmonic calculations. There are three conformers for this molecule. The computational results diagnose the most stable conformer of 3,5-dcpba as the ct form. The geometrical parameters and energies have been obtained for all three conformers from DFT (B3LYP) with 6-311++G(d,p) basis set calculations. The vibrations of stable and unstable conformers of 3,5-dcpba are researched by using quantum chemical calculations. The complete assignments were performed on the basis of the total energy distribution (TED) of the vibrational modes calculated with the scaled quantum mechanics (SQM) method. The stability of the molecule arising from hyperconjugative interactions and charge delocalization has been analyzed using the natural bond orbital (NBO) analysis. The results show that the charge in electron density (ED) in the pi* and sigma* antibonding orbitals and E2 energies confirms the occurrence of intermolecular charge transfer (ICT) within the molecule. Finally, the calculation results were applied to simulated infrared and Raman spectra of the title compound, which show agreement with the observed spectra. Copyright (C) 2010 John Wiley & Sons, Ltd.