Donorsubstituierte 2,4‐Diazacyclopentadienone und indigoide 1,3,5,7‐Tetraazafulvalene

Donor Substituted 2,4‐Diazacyclopentadienones and Indigoid 1,3,5,7‐Tetraazafulvalenes Hydrolysis of tris(diethylamino)imidazolylium chloride gives rise to 2,5‐bis‐diethyl‐amino‐4H‐imidazolin‐4‐one; thiolysis leads, depending on conditions, to 2,5‐bis‐diethylamino‐4H‐imidazolin‐4‐thione or potassium 2,6‐bis‐diethylamino‐1,3,5,7‐tetraazafulvalene‐4,8‐dithiolate. The latter can be protonated to form green 2,6‐bis(dimethylamino)‐3,4,7,8‐tetrahydro‐1,3,5,7‐tetraaza‐fulvalen‐4,8‐dithione, a new indigoid compound, and alkylated to give blue 2,6‐bis‐diethylamino‐4,8‐bis‐alkylthio‐1,3,5,7‐tetraazafulvalenes. Treatment of 2,5‐bis‐diethylamino‐4H‐imidazolin‐4‐thione with copper furnishes 2,6,4,8‐tetrakis‐diethylamino‐1,3,5,7‐tetraazafulvalene. – Oxidation of 2,6‐bis‐dimethylamino‐3,4,7,8‐tetrahydro‐1,3,5,7‐tetraazafulvalen‐4,8‐dithione gives rise to (2,2′‐bis‐diethylamino‐4,4′‐bi(4H‐imidazol)‐5,5′‐dithione, corresponding to dehydroindigo, and reduction leads to a colorless compound, corresponding to leucoindigo.