Experimental, quantum chemical and natural bond orbital investigations of N-(2,4-dimethylphenyl)-2,2-dichloroacetamide and N-(3,5-dimethylphenyl)-2,2-dichloroacetamide

► FTIR and FT-Raman investigations of N-(2,4-dimethylphenyl)-and N-(3,5-dimethylphenyl)-2,2-dichloroacetamide were carried out. ► Energy, structural and thermodynamical characteristics were determined. ► Detailed NBO analyses were carried out. ► The electronic properties and energy of the frontier molecular orbitals were measured. ► Effects of methyl groups on the amide group modes have been analysed.