Crystal structures of 4-chloropyridine-2-carbo¬nitrile and 6-chloropyridine-2-carbonitrile exhibit different intermolecular n-stacking, C—H⋯Nnitrile and C—H⋯Npyridine interactions

The two title compounds are isomers of C₆H₃ClN₂ containing a pyridine ring, a nitrile group, and a chloro substituent. The mol­ecules of each compound pack together in the solid state with offset face-to-face π-stacking, and inter­molecular C—H⋯N_nitrile and C—H⋯N_pyridine inter­actions. 4-Chloro­pyridine-2-carbo­nitrile, (I), exhibits pairwise centrosymmetric head-to-head C—H⋯N_nitrile and C—H⋯N_pyridine inter­actions, forming one-dimensional chains, which are π-stacked in an offset face-to-face fashion. The inter­molecular packing of the isomeric 6-chloro­pyridine-2-carbo­nitrile, (II), which differs only in the position of the chloro substituent on the pyridine ring, exhibits head-to-tail C—H⋯N_nitrile and C—H⋯N_pyridine inter­actions, forming two-dimensional sheets which are π-stacked in an offset face-to-face fashion. In contrast to (I), the offset face-to-face π-stacking in (II) is formed between mol­ecules with alternating orientations of the chloro and nitrile substituents.