Crystal structure of 7,8-dichloro-4-oxo-4H-chromene-3-carbaldehyde

In the title compound, C10H4Cl2O3, a dichlorinated 3-formylchromone derivative, the fused-ring system is slightly puckered [dihedral angle between the benzene and pyran rings = 3.66 (10)degrees]. The dihedral angle between the pyran ring and the formyl plane is 8.64 (7)degrees. In the crystal, molecules are linked through pi-pi stacking interactions [centroid-centroid distance between the benzene and pyran rings = 3.727 (2) angstrom], C-H center dot center dot center dot O hydrogen bonds and short C center dot center dot center dot O contacts [2.838 (4) angstrom]. Halogen bonds between the formyl O atoms and the Cl atoms at the 7-position [Cl center dot center dot center dot O = 2.984 (3) angstrom, C-Cl center dot center dot center dot O = 170.83 (12 degrees and Cl center dot center dot center dot O-C = 116.05 (19)degrees] are also formed along the a axis, resulting in helical structures constructed by C-H center dot center dot center dot O hydrogen bonds and Cl center dot center dot center dot O halogen bonds along the b axis. In addition, type II halogen-halogen contacts between the chlorine atoms at the 7- and 8-positions [Cl center dot center dot center dot Cl = 3.519 (2)angstrom, CCl center dot center dot center dot Cl = 171.24 (10)degrees and 88.74 (11)degrees] are observed.