Chemistry of amidines. Part 4. Analysis of conformation for a series of N′-pyridylformamidines by1H NMR spectroscopic, molecular mechanical and semi-empirical molecular orbital methods

Abstract

The results of NOE measurements for a series of N′-pyridylformamidines and their conjugate acids have been interpreted with the aid of molecular mechanical and semi-empirical molecular orbital calculations. Conformations about the pyridyl–Nim and the Cf–Nam bonds are determined by delocalisation of the Nam lone pair, dipolar interactions, steric interactions and, in the conjugate acids, long range interaction between the pyridyl N and the electron-deficient formyl H.