Synthesis, Spectrometric Characterization, X-Ray Crystallography and Quantum Chemical Calculations of 2-oxo-2H-chromen-7-yl Propionate

The title compound, (I), has been solved by direct methods and refined to a final R value of 0.038 for 1835 independent reflections. In the structure, the planar [r.m.s deviation = 0.014 A] chromen-2-one ring and the 7-propionate side chain are inclined to one another at an acute angle of 65.34(9)°. The molecules form R44 (30) tetrameric units via C—H···O interactions which extend into layers approximately parallel to the ab plane. Furthermore, the crystal structure is supported by π–π stacking interactions between neighbouring benzene and pyrone or coumarin rings [centroid–centroid distances in the range 3.6097(8)–3.6475(9)A], as well as C–H···π interactions [H···centroid distances in the range 2.95–3.00A]. The molecular geometry of (I) was also optimized using density functional theory (DFT/RB3LYP), RMP2 and RHF methods with the 6-311++G(d, p) basis set in ground state. The theoretical data resulting from these quantum chemical calculations are in good agreement with the observed structure, although the observed C—O—C—C torsion angle between the coumarin ring system and the 7-propionate side chain (121.49 (16)°) is somewhat lower than the DFT/RB3LYP calculated value (132.32°) and larger than the RMP2 (114.65°) and the RHF (69.19°) values. Hirshfeld surface analysis has been used to confirm and quantify the supramolecular interactions.