2-(3-Chloro-5,6-diphenyl-2,5-dihydro-1,2,4-triazin-5-yl)-2-methylpropanenitrile

The title compound, C19H17ClN4, was obtained from the reaction of 3-chloro-5,6-diphenyl-1,2,4-triazine with isobutyronitrile in the presence of lithium diisopropylamide as an unexpected product of covalent addition of isobutyronitrile carbanion to the C-5 atom of the 1,2,4-triazine ring. The 2,5-dihydro-1,2,4-triazine ring is essentially planar (r.m.s. deviation = 0.0059 ) and the 5- and 6-phenyl substituents are inclined to its mean plane with dihedral angles of 89.97 (4) and 55.52 (5)°, respectively. Intramolecular C—H...N interactions occur. In the crystal, molecules related by a c-glide plane are linked into zigzag chains along [001] by N—H...N hydrogen bonds.