A DFT and MP2 Study on the Molecular Structure and Vibrational Spectra of Halogenosubstituted Phosphoryl and Thiophosphoryl Compounds

The molecular geometrical parameters, rotational constants, dipole moments and vibrational infrared properties of a series of phosphoryl compounds (OPX _i Y _j Z _k , X, Y, Z = F, Cl, Br; i+ j + k = 3) and their thio analogs are predicted by density functional and MP2 calculations using the 6-311G(2d,2p) basis set. Both methods yielded similar results. The predicted molecular parameters and the vibrational Raman and infrared spectra agree well with the available experimental data. The Raman Scattering Activities (RSA) and depolarization ratios (Dep) of the molecules are obtained by DFT calculations. Considering the different substitution modes of various halogen atoms, the resultant changes in the geometrical and vibrational properties are discussed. Such studies permit detailed information to be obtained concerning unknown molecules and can define the guidelines for synthesizing molecules of particular characteristics.