MOLECULAR CONSTANTS OF SPF3 SPCL3 AND SPBR3 . A NOTE ON P-S BOND AND ITS STRETCHING FREQUENCY

A normal-coordinate analysis has been performed for SPX3 molecules (X = F, Cl, Br). Calculated mean amplitudes of vibration, Coriolis coupling constants and thermodynamic functions are reported. The position of the v(PS) frequency in the three compounds is discussed: it is found to be influenced by force-constant changes in addition to the mechanical coupling. It is also concluded that strong π bonds exist in these molecules. Only recently the assignments which are supposed to be correct for SPF3 and SPBr3 have been published1; in several papers the question has been discussed whether the position of v(PS) is influenced mainly by mechanical coupling, or also by changes in the PS force constants2. Therefore we have reconsidered this problem, and performed a normal-coordinate analysis for the compounds SPX3 (X = F, Cl, Br). © 1969.