Experimental (FT-IR and FT-Raman spectra) and theoretical (ab initio HF, DFT) study of 2-chloro-5-methylaniline

In this work, the experimental and theoretical vibrational spectra of 2-chloro-5-methylaniline (2Cl5MA, C7H8NCl) were studied. FT-IR and FT-Raman spectra of 2Cl5MA in the liquid phase were recorded in the region 4000–400 cm−1 and 3500–50 cm−1, respectively. The structural and spectroscopic data of the molecule in the ground state were calculated by using Hartree–Fock and density functional method (B3LYP) with the 6-31G(d), 6-31G(d,p), 6-31+G(d,p), 6-31++G(d,p), 6-311G(d), 6-311G(d,p), 6-311+G(d,p) and 6-311++G(d,p) basis sets. The vibrational frequencies were calculated and scaled values were compared with experimental FT-IR and FT-Raman spectra. The observed and calculated frequencies are found to be in good agreement. 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 optimized geometric parameters (bond lengths and bond angles) were compared with experimental values of aniline and p-methyl aniline molecules.