A theoretical study of methylphosphine CH₃PH₂ and selected isotopomers: Vibrational analysis and infrared spectra

The normal mode frequencies and the corresponding vibrational assignments of methylphosphine and selected deuterated methylphosphines are studied theoretically. The GAUSSIAN 98 quantum chemistry code was used at the HF, MP2 and DFT/B3LYP level of theory with the 6-311G**basis set. Comparison was made for the infrared spectra of methylphosphine and its deuterated isotopomers between our theoretically predicted values and the experimentally determined vibrational frequencies. Correction factors of the calculated frequencies compared to the experimental values are reported for methylphosphine and its deuterated isotopomers for predominant vibrational motions. The root mean square deviation is reported as a measure of the quality of the predicted frequencies compared to the experimental values.