The Relation Between the Energy of a Hydrogen Bond and the Frequencies of the O–H Bands

It has previously been pointed out (1) that there appears to be a relation between the energy of a hydrogen bond and the shift of the frequency of the O-H bands which accompanies the formation of the bond. Recently additional data have been obtained in this laboratory (2,3) which confirm the existence of this useful relation and it seems worth while to discuss them in this connection. data here presented all relate to linkages in which a hydroxyl hydrogen is concerned, though the atom to which it is weakly bound may be oxygen, chlorine, or carbon in an aromatic ring. It is surprising that the same connection between energy and frequency shift should be found in these various cases but such appears to be the fact. For other types of bond, for example those involving the hydrogen of an amino group, a slightly different relation may well be expected.