Crystal structures of 2-(4-nitro­phen­yl)-3-phenyl-2,3-di­hydro-4H-1,3-benzo­thia­zin-4-one and 2-(2-nitro­phen­yl)-3-phenyl-2,3-di­hydro-4H-1,3-benzo­thia­zin-4-one

The crystal structures are reported of the isomeric compounds 2-(4-nitro­phen­yl)-3-phenyl-2,3-di­hydro-4H-1,3-benzo­thia­zin-4-one, (I), and 2-(2-nitro­phen­yl)-3-phenyl-2,3-di­hydro-4H-1,3-benzo­thia­zin-4-one, (II), both C(20)H(14)N(2)O(3)S, being the para-nitro and ortho-nitro forms, respectively, the meta-form of which is known [Yennawar et al. (2013). Acta Cryst. E69, o1679]. The six-membered thia­zone ring fused with a benzene ring displays a screw-boat conformation with a total puckering amplitude of 0.627 (1) Å in (I), and a near screw-boat conformation with a total puckering amplitude of 0.600 (1) Å in (II). The dihedral angles between the planes of the substituent nitrophenyl and phenyl and rings with the benzene ring of the parent benzo­thia­zone moiety are 75.93 (5) and 82.61 (5)° [in (I)], and 76.79 (6) and 71.66 (6)° [in (II)]. Weak inter­molecular C—H⋯O hydrogen-bonding inter­actions between aromatic H-atom donors and both a nitro-O atom and a thia­zone O-atom acceptor in (I) and a thia­zone O atom in (II) are present, forming in (I) a centrosymmetric 22-membered cyclic dimer which is extended through a similar inversion-related 14-membered cyclic hydrogen-bonding association into a zigzag chain structure extending along c. In (II), a single inter­molecular C—H⋯O hydrogen bond gives a chain structure extending along b. In addition, weak C—H⋯π inter­actions are present in both structures [minimum C⋯ring-centroid separations = 3.630 (2) and 3.581 (2) Å, respectively].