FT-IR, FT-Raman spectra and ab initio HF and DFT calculations of 4-N,N′-dimethylamino pyridine

In this work, we will report a combined experimental and theoretical study on molecular and vibrational structure of 4-N,N′-dimethylamino pyridine (4NN′DMAP). The Fourier transform infrared and Fourier transform Raman spectra of 4NN′DMAP was recorded in the solid phase. The optimized geometry was calculated by HF and B3LYP methods with 6-31G(d,p) and 6-311++G(d,p) basis sets. The harmonic vibrational frequencies, infrared intensities and Raman scattering activities of the title compound were performed at same level of theories. The scaled theoretical wavenumber showed very good agreement with the experimental values. The thermodynamic functions of the title compound was also performed at HF/6-31G(d,p) and B3LYP/6-311++G(d,p) level of theories. A detailed interpretation of the infrared and Raman spectra of 4NN′DMAP was reported. The theoretical spectrograms for FT-IR and FT-Raman spectra of the title molecule have been constructed.