2,8,17-Trithia[4 5 , 1 2 ] [9] metacyclophan-4-ene, a cyclophane with a tertiary olefin strapped across the face of a benzene ring, has been prepared and its X-ray structure determined. The olefin is pyramidalized toward the benzene ring. The X-ray structure of the corresponding saturated phane (in-2,8,17-trithia[4 5 , 1 2 ] [9] metacyclophane, which was synthesized previously) has also been determined. The structure and reactivity of the in-olefin are discussed in the context of other structures and the results of computational studies.