Hückel molecular orbital study of the non-additivity of proton chemical shifts in ortho-substituted phenols
Abstract
The non-additivity of the proton chemical shifts of pyrocatechol and pyrogallol can be rationalised in terms of a hydrogen-bonding interaction between the adjacent hydroxy-groups, but not by a non-bonding interaction between adjacent oxygen atoms. Electron densities were calculated by the Hückel molecular orbital method, with account taken of the two effects.