CORRELATIONS BETWEEN AB-INITIO AND EXPERIMENTAL-DATA FOR ISOLATED H-BONDED COMPLEXES OF WATER WITH NITROGEN BASES

Correlations between selected ab initio predicted and experimentally o bserved properties of 1:1 H-bonded complexes of pyridines, pyrimidines , and imidazoles with water are investigated. Relationships are found between the experimental proper ties of proton affinity and water freq uency shift, and the ab initio calculated bond distances, interaction energies and water frequency shifts. It is also found that well-define d relations can be established between calculated and observed propert ies for the pyridine complexes, but these cannot be reliably extended to the other N-base systems. The similarities demonstrate that the pre sently available ab initio methods are useful in predicting the experi mental behaviour of H-bonded systems, but only for closely related mol ecules. (C) 1997 Elsevier Science B.V.