A triboluminescent europium(III) complex

The crystal structure of (4,4′‐di­methyl‐2,2′‐bipyridyl)­tris­3,3,3‐tri­fluoro‐1‐(2‐thenoyl)propan‐2‐onato]­europium(III), or more commonly (4,4′‐dimethyl‐2,2′‐bipyridyl)tris(2‐thenoyltrifluoro­acetonato)europium(III), Eu(C₈H₄F₃O₂S)₃(C₁₂H₁₂N₂)], has been determined. Crystals of the complex emit vivid red light when scratched or fractured. This triboluminescent activity seems to correlate with the non‐centrosymmetric crystal structure and disorder of the thienyl rings and CF₃ groups which is present here and in similar compounds. While modeling the thienyl‐ring disorder, it was noted that the bond angle at the C atom replaced by S is a sensitive sign of even small rotational ring disorder. The coordination geometry of the Eu^III ion can be described as square antiprismatic, with coordination by the six O atoms of the three chelating β‐diketonate ligands and the two N atoms of the neutral bipyridyl ligand.