Source of materialA mixture of the 4-chloroindoline-2,3-dione (0.18 g, 1.0 mmol) and 4-benzylpiperazine-1-carbothiohydrazide (0.25 g, 1.0 mmol) in absolute methanol (20 mL) was stirred at room temperature for 3 days. Thin layer chromatography (TLC) of the solution indicated the end of the reaction (R f = 0.40, dichloromethane/methanol = 95:5, v/v). The precipitates were collected by filtration and dried in air, which was purified by recrystallization from ethanol to give the title compound (yield 40%; m.p. 497-498 K). Yellow single crystals suitable for X-ray diffraction were grown from a mixture of dichloromethane and methanol (5:1, v/v) by slow evaporation at room temperature.