Infrared and Raman spectrum, molecular structure and theoretical calculation of 3,4-dichlorophenylboronic acid

In this work, the experimental and theoretical study on the structures and vibrations of 3,4-dichlorophenylboronic acid (3,4-dcpba, C6H3B(OH)2Cl2) are presented. The Fourier Transform Infrared spectra (4000–400 cm−1) and the Fourier Transform Raman spectra (3500–5 cm−1) of the title molecule in the solid phase have been recorded. There are four conformers for this molecule. The computational results diagnose the most stable conformer of 3,4-dcpba as the ct form. The geometrical parameters and energies have been obtained for all four conformers from DFT (B3LYP) with 6-311++G(d,p) basis set calculations. The vibrations of stable and unstable conformers of 3,4-dcpba are researched with the aid of quantum chemical calculations. The complete assignments were performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. The molecular structures, vibrational frequencies, Infrared intensities and Raman scattering activities were calculated. The spectroscopic and theoretical results are compared. The optimized bond lengths, bond angles and calculated frequencies showed the excellent agreement with the experimental results. The theoretical spectrogram for the Infrared and Raman spectrum of the title molecule has been constructed.