5-Fluoro-3-(2-phenylhydrazinylidene)indolin-2-one

In the title compound, C14H10FN3O, the six- and five-membered rings of the isatin moiety and the six-membered ring of phenylhydrazone are nearly planar with r.m.s. deviations of 0.0003, 0.0004 and 0.007 Å, respectively. The dihedral angle between the phenyl ring and the isatin ring system is 6.09 (9)°. The molecular structure is stabilized by a strong intramolecular N—H⋯O hydrogen bond, leading to the formation of a pseudo-six-membered ring, generating an S(6) ring. The crystal structure features intermolecular N—H⋯O interactions.