Enhanced Stability of Non-Proton-Transferred Clusters of Hydrated Hydrogen Fluoride HF(H2O)n (n = 1−7): A Molecular Orbital Study

The results of a molecular orbital study on structures and stabilities are presented for the hydrated clusters of the hydrogen fluoride (HF) molecule, HF(H 2 O) n ( n = 1−7). For each cluster system, the most stable structure is found to be the non-proton-transferred type, but not the ion-pair form. The computational results are quite consistent with the weak acidity of the HF in water. The differences between HF(H 2 O) n and HCl(H 2 O) n cluster systems are further discussed for the structure and stability depending on the cluster size. The calculated IR spectra of the stable HF(H 2 O) n clusters predict large red-shifts of H−F and hydrogen-bonded O−H stretching frequencies.