Infrared Spectra of 34S Thionophosphate Esters

Abstract

Since we had hoped to be able to use the P=S frequency to monitor the progress of sulfur addition reactions, we undertook the present study to firmly establish the positions of that band in the spectra of compounds of interest. To be sure, assignment of a given band in the spectrum of a complex molecule to a particular localized motion is only an approximation. Nevertheless, we hoped that the spectra of isotopically substituted compounds might provide some information about the extent to which the P=S vibration could be considered to be an isolated motion. In addition we hoped that some insight could be gained into the nature of the interactions which stabilize the rotational isomers. To our knowledge, no 34S spectra of thionophosphate esters appear in the literature, except for those cited in conference proceedings,6 reported by us.