Journal of Molecular Structure. Theochem vol:487 issue:1-2 pages:27-31
Computational calculations have been carried out at the B3-LYP/6-31 + + G** and RHF/6-31 + + G** levels of theory to determine the equilibrium structures of complexes formed between the tautomers 2-hydroxypyridine and 2-oxopyridine with HCl. Different types of hydrogen-bonding have been found: two closed complexes of type III (proton transfer), each containing two hydrogen bonds i.e. N-H+...Cl-...H-O and C=O-H+...Cl-...H-N, two open complexes of intermediate type I --> II: (NHCl)-H-...-Cl-... and C=(OH)-H-...-Cl, and one open complex of type I: H-(OH)-H-...-Cl. A comparison of the experimental and calculated IR frequencies demonstrates that the most accurate spectral parameters are predicted by the B3-LYP/6-31 + + G** method, especially when this method is used with a set of different scaling factors. (C) 1999 Elsevier Science B.V. All rights reserved.