Experimental and DFT studies on the vibrational and electronic spectra of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone

Vibrational and electronic spectral measurements were made for 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). Optimized geometrical structure and harmonic vibrational frequencies were computed by DFT(B3LYP, CAMB3LYP, B3P86, M062X, mPW3PBE and PBE1PBE) using 6-311++G(d,p) basis set. Complete assignments of the observed spectra were proposed. The absorption spectra of the compound were computed both in gas-phase and in CH2Cl2 solution using TDCAMB3LYP/6-311++G(d,p) and PCM-TDCAMB3LYP/6-311++G(d,p) approaches, respectively, the calculated results provide a good description of positions of the bands maxima in the observed electronic spectrum.

Graphical abstractDFT study of the structural and spectroscopic properties of DDQ has been reported.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The FT-IR, FT-Raman spectra and UV–vis of the title compound have been recorded experimentally. ► Optimized geometry, vibrational frequencies, IR and Raman intensities are obtained with six DFT methods. ► The complete assignments of the experimental spectra are performed on the basis of the potential energy distribution (PED). ► The HOMO and LUMO energies have been calculated. ► The absorption spectra of the compound were computed both in gas-phase and in CH2Cl2 solution.