GIAO/DFT calculated chemical shifts of tautomeric species. 2-Phenacylpyridines and (Z)-2-(2-hydroxy-2-phenylvinyl)pyridines

✍ Scribed by Borys Ośmiałowski; Erkki Kolehmainen; Ryszard Gawinecki

• Book ID: 102527019
• Publisher: John Wiley and Sons
• Year: 2001
• Tongue: English
• Weight: 115 KB
• Volume: 39
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.856

✦ Synopsis

Abstract

^1^H, ^13^C and ^15^N NMR chemical shifts for 28 substituted 2‐phenacylpyridines (ketimine forms) and their enolimine tautomers, (Z)‐2‐(2‐hydroxy‐2‐phenylvinyl)pyridines, were calculated via the GIAO/DFT approach. Among four tested methods at the B3LYP level of theory, the 6–311G, 6–311++G and 6–311G^**^ basis sets gave acceptable result for ^13^C NMR chemical shifts whereas the 6–311++G^**^ basis set was the minimum needed for reproduction of ^15^N NMR chemical shifts. Satisfactory reproduction of ^13^C and ^15^N NMR chemical shifts for different tautomers revealed that intramolecular hydrogen bonding could be modeled reliably by these calculations when the geometry optimizations were done with the HF/3–21G method. Agreements between theoretical and experimental ^13^C and ^15^N NMR chemical shifts and also HF/3–21G and HF/6–31G^**^ optimized structural parameters with those obtained by x‐ray crystallographic measurements suggests that it is not necessary to select too sophisticated and CPU time‐intensive methods for geometry optimizations. Copyright © 2001 John Wiley & Sons, Ltd.