Ethyl 1-ethyl-7-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylate: X-ray and DFT studies

The basic building unit in the structure of the title compound, C14H14FNO3, is pairs of molecules arranged in an antiparallel fashion, enabling weak C-H...O interactions. Each molecule is additionally involved in π-π interactions with neighbouring molecules. The pairs of molecules formed by the C-H...O hydrogen bonds and π-π interactions form ribbon-like chains running along the c axis. Theoretical calculations based on these pairs showed that, although the main intermolecular interaction is electrostatic, it is almost completely compensated by an exchange-repulsion contribution to the total energy. As a consequence, the dominating force is a dispersion interaction. The F atoms form weak C-F...H-C interactions with the H atoms of the neighbouring ethyl groups, with H...F separations in the range 2.59-2.80 \uc5