Structural study of a new 1-(2-thienyl)-3-(3-methyl-2-thienyl)-propenone, in-situ radiation-induced dimerization products

The new conjugated system ("chalcone kind") reported herein, 1-(2-thienyl)-3-(3-methyl-2-thienyl)-propenone, C₁₂H ₁₀OS₂ presents a monomeric molecular structure, and it most interesting aspects are to be found in it intermolecular interactions, of varied type (C-H⋯O, C-H⋯π, π⋯π) and strength. Some anomalies detected in the refinement process, however, provided evidence that an unexpected in-situ, radiation-induced dimerization reaction had taken place during data collection, with the starting and final products coexisting in a topotactic fashion. This effect is depended of structural packing; that is not all this kind of conjugated system presents this effect. The main factor is the distance between the double bonds of neighboring monomers(about 3 Å).