Effect of deuteration on hydrogen bonds

A study of the 1 : 1 interaction of CH3OD and t-C4H9OD as well as the corresponding hydroxy derivatives with electron donor molecules has shown that the enthalpies of formation of complexes are generally increased by ∼1 to 2 kJ mol–1 on deuteration. Enthalpies of dimerization of t-C4H9OH and t-C4H9OD are comparable. Deuterium bond energies may be lower than hydrogen bond energies only for very short hydrogen bonds. The shift in the O—H stretching frequency Δtext-decoration:overlineνOH is related to Δtext-decoration:overlineνOD by the relation, Δtext-decoration:overlineνOH≈ 1.414 Δtext-decoration:overlineνOD as expected on the basis of mass effect alone.