Knowledge Bank

“It has previously been demonstrated that the stretching frequency of the P $=$ O and C $=$ O groups increases in a linear fashion with an increase in the sum of the electronegativities of adjacent substituents. Evidence of similar relationships for the stretching frequencies of the $SO2$, $NO2$, and $C=S$ groups will be presented. The slopes of the straight line for the $C=O,P=OSO2$ and $C=$ S group plots of frequency vs. electronegativity sum are found to be very nearly equal, which may have implications in regard to the relative contributions of the inductive and mesomeric effects of the substituents. It has been possible to assign effective electronegativity values to polyatomic groups which can usually be used in all the correlations.”