Studies on Diamagnetic Susceptibility of Biologically Active Heterocycles, Part 2 Diamagnetic Susceptibilities of 4H-1,4-Benzothiazines and their Sulfones

Abstract

Diamagnetic susceptibilities for a number of 4H-1,4-benzothiazines and their sulfones are reported. A theoretical method to estimate diamagnetic susceptibilities of 4H-1,4-benzothiazines is also reported. Benzothiazine has been considered to be composed of two units, one consisting of a benzene ring containing amino and thio groups at ortho positions with other substituents and other consisting of β-diketones/β-ketoesters. Diamagnetic contributions of these two units have been calculated from diamagnetic susceptibilities of substituted o-aminobenzenethiols and β-diketones/β-ketoesters and have been used in estimating diamagnetic susceptibilities of 1,4- benzothiazines. It has provided excellent results of theoretical diamagnetic susceptibility. Such an excellent agreement between experimental and theoretical results has been attributed to the fact that the interactions between substituents, which do affect diamagnetism, have been duly accounted for in such calculations. Diamagnetic susceptibility contribution of oxygen atoms attached to sulphur forming sulfone group is also reported.