The Relation between the Bridge Length of Short Hydrogen Bonds, the Potential Curve, and the Hydroxyl Stretching Frequency

Recent spectroscopic results on substances with short hydrogen bonds are compared with predictions from semi‐empirical models [1, 2]. It is shown on hand of examples that hydrogen bonds with O ··· O distances between 2.41 and 2.61 Å may be either of the single minimum symmetric type or of the double minimum type independently of this distance. Some important structural factors are discussed. The empirical relationships [3, 4, 5] between the bridge length and the OH stretching frequencies are revised, and the importance is stressed of the chemical character of groups participating in the hydrogen bond in determining the frequency.