Fully and partially fluorinated flavone derivatives

In the crystal structures of the fully and partially fluorinated flavone derivatives 5,6,7,8-tetra-fluoro-2-(2,3,4,5,6-penta-fluoro-phen-yl)-4H-1- benzopyran-4-one, C₁₅HF₉O₂, (I), and 5,6,7,8-tetra-fluoro-2-phenyl-4H-1-benzopyran-4-one, C₁₅H ₆F₄O₂, (II), the penta-fluoro-phenyl group and the pyran-one moiety in (I) are twisted due to repulsion of the F substituents, and a CO(δ^-)⋯π(δ⁺) inter-molecular inter-action is observed between the carbonyl O atom and the penta-fluoro-phenyl group. In (II), on the other hand, the phenyl group and the pyran-one moiety are almost coplanar, and arene-perfluoro-arene inter-actions are observed in the head-to-tail inter-molecular columnar stacking between the phenyl group and the tetra-fluoro-phenyl-ene moiety.