Molecular structure and vibrational study on 2,3-dihydro-1H-indene and its derivative 1H-indene-1,3(2H)-dione by density functional theory calculations

2,3-Dihydro-1H-indene also known as indan is a simple hydrocarbon petrochemical compound, whereas its derivative 1H-indene-1,3(2H)-dione is an anticoagulant which help prevent the blood coagulation. The equilibrium geometries and harmonic frequencies of both molecules under investigation were determined and analyzed at DFT level employing the basis set 6-311, which is augmented by d and p polarization as well as diffuse functions. The skeleton of both the optimized molecules is non-planar. In general, a good agreement between experimental and calculated normal modes of vibrations has been observed. The calculated frontier orbital energy gap and the dipole moment data also support the fact that the 1H-indene-1,3(2H)-dione is the more reactive molecule and more polar than 2,3-dihydro-1H-indene molecule. The molecular electrostatic potential surface displays how the activity varies from 2,3-dihydro-1H-indene to its derivative 1H-indene-1,3(2H)-dione.