Ultraviolet spectral correlation between the cation of an amino-N-heteroaromatic compound and the neutral species of the corresponding oxo-analogue

Abstract

A new spectroscopic correlation is described, namely that the cation of a 2-amino-derivative of pyrimidine (or of a fused pyrimidine) has an u.v. spectrum similar to that of the neutral species of the 2-oxo-analogue. This correlation (which does not extend to the 4-derivatives) is attributed to a formal similarity between the guanidinium and the urea types of resonance. Correlation was found to be less tight in the corresponding pyridine series, where amidinium and amide resonances were concerned.