THE QUANTITATIVE PREDICTION AND INTERPRETATION OF THE VIBRATIONAL-SPECTRA OF ORGANOPHOSPHORUS COMPOUNDS .5. METHOXYDIFLUOROPHOSPHINE CH3OPF2-ALPHA

The results of ab initio SCF/6-31G** calculations are reported for the energies, rotational constants and dipole moments of several conformers of methoxydifluorophosphine CH3OPF2. The energies of the conformers predicted at the MP4(SDTQ)/6-31G** level are used for discussion of the barriers for rotation of the CH3 and PF2 groups. The geometries of the lowest energetic conformer optimized at the SCF/3-21G*, SCF/6-31G** and MP2/6-31G** levels are also reported. The best agreement of the predicted geometrical parameters with the experimental values is for the SCF/6-31G** calculations, but none of the calculations reproduce the experimentally observed difference between the lengths of the PF and PO bonds. The calculated (SCF/3-21G* and SCF/6-31G**) vibrational spectrum (wavenumbers and intensities) of the global minimum conformer agrees well with the experimental spectrum in the gas phase. The calculations predict correctly the shifts of the IR wavenumbers of the molecule upon deuteration of the parent compound.