Beschreibung:
<jats:p> Tautomerism of dibenzothiazolylmethane (1) and its C-methyl derivative (2) has been studied by <jats:sup>1</jats:sup>H nuclear magnetic resonance, ultraviolet, and infrared spectroscopy using C,C-dimethyl (3) and N-methyl (4) derivatives as model compounds of the "CH" and "NH" forms, respectively. X-ray diffraction analysis of the "fixed" N-methyl derivative 4 shows that it corresponds to the Z-sE isomer 4b<jats:sub>2</jats:sub>. The CH tautomers are unstable in solution and they slowly isomerize into a mixture of NH tautomers that depends on the solvent and on the C-substituent (H or CH<jats:sub>3</jats:sub>). </jats:p>