Optimized geometry, vibration and NMR spectra of cycloketones and benzocycloketones: Atheoretical study

Moller-Plesset second-order (MP۲), Hartree–Fock (HF) and Density functional theory(DFT) were used to investigate the structure, vibrational frequencies, some energies andabsolute NMR shielding of cyclic carbonyl compounds. A models of MP۲ and B۳LYPwith ۶-۳۱۱G, ۶-۳۱۱G** and ۶-۳۱۱++G** basis set are used to optimize and locate theenergy minimum of the title compounds. For small ring sizes (n = ۳–۶), calculatedmolecular geometries, dipole moments, moments of inertia, and vibrational spectra werecompared to experimental data. Vibrational frequencies at the same level of theory arecalculated with assignment of each band frequency. In this work three main effects werestudied: the size of the ring, the inclusion of oxygen atoms in the ring and benzene ringaddition.