Acta Crystallographica Section C

Crystal Structure Communications

Volume 64, Part 9 (September 2008)


organic compounds



fa3158 scheme

Acta Cryst. (2008). C64, o498-o501    [ doi:10.1107/S0108270108025377 ]

Hydrogen-bonding versus [pi]-[pi] stacking interactions in dipyrido[f,h]quinoxaline-6,7-dicarbonitrile and 6,7-dicyanodipyrido[f,h]quinoxalin-1-ium chloride dihydrate

L. Kozlov and I. Goldberg

Abstract: The solvent-free title compound, C16H6N6, is an aromatic derivative of phenanthroline with an extended [pi] system. It exhibits a remarkable [pi]-[pi] columnar stacking in the crystal structure, with interplanar distances of 3.229 (3) and 3.380 (3) Å, the shorter spacing being between the two molecules within the asymmetric unit. Adjacent units along the stacked arrays are rotated in-plane with respect to one another by approximately 120°. The hydrochloride derivative, C16H7N6+·Cl-·2H2O, in which one of the phenanthroline N atoms has been protonated, crystallized as a dihydrate. The supramolecular organization in this compound is characterized by continuous hydrogen bonding between the component species, yielding two-dimensional hydrogen-bonded networks. This study demonstrates the high significance of the [pi]-[pi] stacking interactions in the solvent-free aromatic system and how they can be undermined by introducing hydrogen-bonding capacity into the ligand.

Formula: C16H6N6 and C16H7N6+·Cl-·2H2O


hkldisplay filedownload file

Structure factor file (CIF format) (212.7 kbytes)
[ doi:10.1107/S0108270108025377/fa3158Isup2.hkl ]
Contains datablock I


hkldisplay filedownload file

Structure factor file (CIF format) (153.2 kbytes)
[ doi:10.1107/S0108270108025377/fa3158IIsup3.hkl ]
Contains datablock II


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