Intermolecular C--H· · ·O, Cl· · ·Cl and pi-pi interactions in the 2-dichloromethyl derivative of vitamin K3

The title 1,4-naphthoquinone, 2-dichloromethyl-3-methyl-1,4- dihydronaphthalene-1,4-dione, C12H8Cl2O2, is a chlorinated derivative of vitamin K3, which is a synthetic compound also known as menadione. Molecules of (I) are planar and lie on a crystallographic mirror plane (Z0 = 0.5) in the space group Pnma. They are connected to each other by C--H O hydrogen bonds, forming two-dimensional layers parallel to the ac plane. In addition, Cl Cl and - interactions link adjacent molecules in different layers, thus forming zigzag ribbons along the b axis, such that a three-dimensional architecture is generated.