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

N-(2,4-Dimethylphenyl)-2,2-dichloroacetamide (24DMPA) and N-(3,5-dimethylphenyl)-2,2-dichloroacetamide (35DMPA) of the configuration XyC6H5-y-NHCO-CHCl2 (where, X=CH3 and y=2) were synthesised and an extensive spectroscopic investigations have been carried out. The ab initio and DFT studies were carried out with 6-31G** and cc-pVDZ basis sets to determine the structural, thermodynamical and vibrational characteristics of the compounds and also to understand the steric influence of methyl groups on the characteristic frequencies of amide (-CONH-) group. The most stable conformer has been determined by PES scan. Normal co-ordinate analysis has been carried out in an effort to provide mixing of the fundamental modes with the help of potential energy distribution (PED). The energies of the frontier molecular orbitals have been determined. Complete NBO analysis was also carried out to find out the intramolecular electronic interactions and their stabilisation energy. All the computed values are well agreed with the experimental data. (C) 2011 Elsevier B.V. All rights reserved.