Molecular structure, vibrational spectra, HOMO, LUMO and NMR studies of methylphenylcyclopropenone based on density functional theories

Abstract

The Fourier-Transform infrared and FT-Raman spectra of Methylphenylcyclopropenone (MPCP) were recorded in the region 4000–100 cm−1. Quantum mechanical calculation of energies, geometrical structure and vibrational wavenumbers of MPCP were carried out using density functional B3LYP method with 6-31G++(d,p) and 6-311G++(d,p) basis set. The computed wave numbers were scaled so as to agree with the observed values and the scaling factors are reported. A study on the electronic properties, such as HOMO and LUMO energies, were performed by time-dependent SCF method. Mulliken charges of the compound were also calculated and interpreted. The thermodynamic properties (heat capacity, entropy, and enthalpy) at different temperatures were calculated in DMSO, chloroform and gas phases and the results are interpreted. NBO analysis is carried out to analyze the charge delocalization of the molecule. The1Hand13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were studied using the gauge independent atomic orbital (GIAO) method.