An infrared study of organophosphorus compounds—I. Rotational isomers and assignments

Infrared liquid and solution spectra were recorded over the range 400–3800 cm⁻¹ at temperatures ranging from 25°C to −100°C for CH₃OP(S)Cl₂, CD₃OP(S)Cl₂, and CH₃OP(O)Cl₂. This study of infrared spectra at several temperatures adds support to a previous conclusion that the absorption bands of ν_PO and ν_PS appear as doublets due to the existence of rotational isomers. In addition, it is shown that the absorption bands of several fundamentals also appear as doublets in the infrared spectrum due to the presence of rotational isomers. Also, the study of the infrared spectrum of CD₃OP(S)Cl₂ has enabled a definite assignment for the fundamentals due to CH₃ and CD₃ groups and the fundamentals for the COPCl₂ skeleton, which occur in the 400–3800 cm⁻¹ region of the spectrum.