On the crystal structures of two inclusion compounds of tris(5-acetyl-3-thienyl)methane

1-(9-ANTHRYL)-2-AROYLETHYLENES Fig. 2 shows the crystal structures.In trans-(IV) nearest neighbouring anthryl groups, which are related by a centre of symmetry, interact with van der Waals contacts.Although the distance between the least-squares planes is ca 3.4 A, one anthryl group is significantly displaced with respect to the other along both the long and short axes of the anthracene, and as a result only a part of the anthracene moiety is involved in the TT-TT interaction.The close.contacts are C(l)•••C(13i) = 3.604 ( 5), C(l)•••C(141) = 3.613 (5), C(2)•••C(l li) = 3.616 (5), C(2)•••C(121) = 3.384 (5), C(2)•••C(13i) = 3.227 (5) and C(3)•••C(l3 1 ) = 3.663 (5) A (i =x,y, 2 -z).In cis-(1), cis-(III) and cis-(IV) there are no stacking interactions observed between the anthryl groups in the nearest neighbouring molecules.The crystal structures of the four compounds explain the lack of reactivity for [4 + 4] photodimerization of anthryl groups in the solid state.The financial support by the Hayashi Memorial Foundation for Female Natural Scientists is acknowledged.This work