THE SYMMETRY GROUP OF LABILE INTRAMOLECULARLY HYDROGEN-BONDED NAPHTHAZARIN

After discussing the changes in the geometry of the molecule naphthazarin (I) caused by the labile hydrogen atoms of the two planar intramolecularly bonded hydroxyl groups, the molecular symmetry group of the molecule is deduced as C(s)(M); this allows the interpretation of the IR and Raman spectra of the compound. The potential opposing the concomitant interchange of two hydrogen atoms is calculated by means of the MINDO/3 semiempirical molecular orbital program. The resulting energy values are fitted to a Morse potential and the energy levels are calculated. There is a possibility of quantum mechanical tunnelling.