Abstract
Crystal structures of four symmetrical 1,3,5,7-tetrasubstituted tricyclo[5.1.0.03,5]octane-2,6-diones have been determined and their packing is discussed. In the absence of strong intermolecular interactions, the methylene groups of the cyclopropane rings form C–H⋯O weak hydrogen bonds which determine the packing of the molecules within the crystal. In the case of syn-isomers, unusual multi-centred interactions have been found.