Beiträge zur Chemie der Pyrrolpigmente, 6. Mitt.: Dipolmomente von substituierten Pyrromethenen

摘要

The dipole moments of three symmetrically and one, unsymmetrically substituted pyrromethene derivatives were determined using cyclohexane as solvent. By comparison of these moments with those obtained from a semiempirical quantum mechanical treatment including all valence electrons (CNDO/2), the predominance of one tautomeric form of the unsymmetrically substituted species was deduced.