2-{3-[2-(1H-Indol-3-yl)vinyl]-5,5-dimethylcyclohex-2-enylidene}malononitrile

The title compound, C21H19N3, first synthesized by Lemke [Chem. Ber. (1970) , 103, 1894-1898], due to its solvatochromic behaviour is supposed to be a good candidate for non-linear optical (NLO) and electrooptical applications . The molecule is nearly planar, with the exception of the C(CH3)(2) group; the disubstituted C atom is displaced by 0.627 (2) Angstrom from the mean plane of the remaining atoms of the cyclohexene ring. The hydrogen bond for med by the indolyl NH group with the N atom of one of the cyano groups [N . . .N 3.168 (3) Angstrom and N-H . . .N 148 degrees], links the molecules i nto infinite chains stretching along the [10 (1) over bar] direction of the crystal. The existence of this hydrogen bond was also confirmed by FT-IR s pectral data [nu (N-H) = 3388 cm(-1) in the solid state (KBr pellet)].