Characteristic infrared absorption frequencies of organophosphorus compounds—II. PO(X) bonds

The characteristic infrared absorption frequencies associated with POH, POP and POC bonds are discussed. It is shown that the observed frequencies can be correlated with the overall chemical structure of the molecule, although not to the same extent as with the phosphoryl (PO) bond. In the case of the PO stretching vibration of the PO(H) bond, a linear relationship, between the vibration frequency and the sum of the phosphorus inductive (π) constants of the substituents attached to the phosphorus atom, is derived.