The crystal structures of four N-(4-halophen­yl)-4-oxo-4H-chromene-3-carboxamides

Four N-(4-halophen­yl)-4-oxo-4H-chromene-3-carboxamides (halo = F, Cl, Br and I), N-(4-fluoro­phen­yl)-4-oxo-4H-chromene-3-carboxamide, C(16)H(10)FNO(3), N-(4-chloro­phen­yl)-4-oxo-4H-chromene-3-carboxamide, C(16)H(10)ClNO(3), N-(4-bromo­phen­yl)-4-oxo-4H-chromene-3-carboxamide, C(16)H(10)BrNO(3), N-(4-iodo­phen­yl)-4-oxo-4H-chromene-3-carboxamide, C(16)H(10)INO(3), have been structurally characterized. The mol­ecules are essentially planar and each exhibits an anti conformation with respect to the C—N rotamer of the amide and a cis geometry with respect to the relative positions of the C(arom)—C(arom) bond of the chromone ring and the carbonyl group of the amide. The structures each exhibit an intra­molecular hydrogen-bonding network comprising an N—H⋯O hydrogen bond between the amide N atom and the O atom of the carbonyl group of the pyrone ring, forming an S(6) ring, and a weak C(arom)—H⋯O inter­action with the O atom of the carbonyl group of the amide as acceptor, which forms another S(6) ring. All four compounds have the same supra­molecular structure, consisting of R (2) (2)(13) rings that are propagated along the a-axis direction by unit translation. There is π–π stacking involving inversion-related mol­ecules in each structure.