Crystal and molecular structure ofo-chlorobenzylidenemalononitrile

The crystal structure ofo-chlorobenzylidenemalononitrile, C₁₀H₅ClN₂, has been determined by X-ray crystallographic analysis. The compound crystallizes in the monoclinic space groupP2₁/c, with unit cell dimensionsa = 3·971,b = 21·140,c = 10·747 Å, = 95·29 °;Z = 4. The structure was solved by matching an assumed molecular shape to the near-origin peaks of a sharpened vector map, the detail being established by Fourier syntheses. Refinement by full-matrix least squares converged to an indexR of 0·097 for 1729 reflections from CuK Weissenberg photographs.The molecular components, the phenyl and malononitrile groups, are individually planar but mutually tilted with a dihedral angle of 12·7 °. The deviation from planarity is related to steric hindrance between the malononitrile group and theortho-hydrogen of the phenyl ring.