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

Abstract

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-iodo-phenyl)-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 supra-molecular 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.