Experimental

R factor = 0.053; wR factor = 0.113; data-to-parameter ratio = 20.6. In the title compound, C15H12N4OS, the dihedral angle between the nine-membered indolin-2-one ring system and the phenyl ring is 2.72 (7). Intramolecular cyclic N—H O and C—H S hydrogen-bonding interactions [graph set S(6)] are present, as are weak N—H N interactions [graph set S(5)]. In the crystal, molecules form centrosymmetric cyclic dimers through pairs of N—H O hydrogen bonds [graph set R2 2(8)] and these are extended by C—H S interactions. The crystal structure also features weak C—H interactions. Related literature For related crystal structures, see: Ali et al. (2012); Qasem Ali et al. (2011a,b); Ferrari et al. (2002); Pervez et al. (2010); Ramzan et al. (2010). For various biological activities of Schiff bases, see: Bhandari et al. (2008); Bhardwaj et al. (2010); Pandeya et al. (1999); Sridhar et al. (2002); Suryavanshi & Pai (2006). For the cytotoxic and anticancer activities of isatin and its derivatives, see: Vine et al. (2009). For graph-set analysis, see Bernstein et al. (1995)