7-Nitro-5H-1-benzothiopyrano[2,3-b]pyridin-5-one

In the molecule of the title compound, C12H6N2O3S, the central heterocyclic ring is oriented at dihedral angles of 3.25 (6) and 2.28 (7)° with respect to the benzene and pyridine rings, respectively. The dihedral angle between the benzene and pyridine rings is 5.53 (7)°. In the crystal structure, intermolecular C—H⋯O hydrogen bonds link the molecules into chains.

In the molecule of the title compound, C 12 H 6 N 2 O 3 S, the central heterocyclic ring is oriented at dihedral angles of 3.25 (6) and 2.28 (7) with respect to the benzene and pyridine rings, respectively. The dihedral angle between the benzene and pyridine rings is 5.53 (7) . In the crystal structure, intermolecular C-HÁ Á ÁO hydrogen bonds link the molecules into chains.

Comment
Pyridine containing compounds are widely distributed in nature. Drugs, dyes, alkoloids (Acheson et al., 1976), nalidixic acid and quinoline (Lesher et al., 1962), which are antibacterial, also contain pyridine rings in their structures. Heteroaromatic antitumor compounds have been prepared in recent years with the hope of increasing pharmacological effects. DNA intercalating agents, which are an important class of antitumor drugs, usually posses planar aromatic and heteroaromatic polycyclic system. Some thioxanthones have also shown effectiveness against tumor (Archer et al., 1982;Archer et al., 1988;Showalter et al., 1988). Heterocyclic compounds having S-atom in their ring can also be used as antioxidative agents.
In the crystal structure, intermolecular C-H···O hydrogen bonds (Table 1) link the molecules into chains (Fig. 2). These H-bonds seem to play an effective role in the stabilization of the structure.

Refinement
H atoms were positioned geometrically, with C-H = 0.93 Å for aromatic H and constrained to ride on their parent atoms with U iso (H) = 1.2U eq (C).
supplementary materials sup-2 Figures   Fig. 1. The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.  as those based on F, and R-factors based on ALL data will be even larger.