Experimental (FT-IR and FT-Raman spectra) and Theoretical (Ab initio/HF, DFT/B3LYP) Study of 2-Amino-5-Chloropyridine and 2-Amino-6-Chloropyridine

Abstract

The Fourier transform infrared (FT-IR) and FT-Raman spectra of 2-amino-5-chloropyridine (2A5CP) and 2-amino-6-chloropyridine (2A6CP) have been recorded in the regions 4000–400 cm^-1 and 4000–100 cm^-1, respectively. The observed FT-IR and FT-Raman data, a complete vibrational assignment and analysis of the fundamental modes of the compounds were carried out. All the geometrical parameters have been calculated by HF and DFT (B3LYP) methods with 6-311++G (d, p) basis set. The vibrational wavenumbers, IR intensities and Raman activities are calculated at the same theory levels used in geometry optimization. The calculated frequencies are scaled and compared with experimental values. The scaled B3LYP/6-311++G(d,p) results show the best agreement with the experimental values. The calculated HOMO–LUMO energies show that charge transfer occurs in the molecules.

Keywords: FT-IR, FT-Raman, ab initio, DFT, 2-amino-5-chloropyridine, 2-amino-6-chloropyridine.