A Study on Electronic Interaction Between two [2.2]Metacyclophane Systems Connected with a CC Bond: Preparation, Structure and Complexation of ( E )‐ and ( Z )‐8,8′‐(Ethene‐1,2‐diyl)bis(5‐ tert ‐butyl[2.2]metacyclophane)

( E )‐8,8′‐(Ethene‐1,2‐diyl)bis(5‐ tert ‐butyl[2.2]metacyclo‐phane) ( 2 ) was obtained from a McMurry reaction of 5‐ tert ‐butyl‐8‐formyl[2.2]metacyclophane ( 1 ). Irradiation of 2 with a high‐pressure mercury lamp gave the corresponding ( Z ) isomer 3 . X‐ray crystallographic analyses of 2 and 3 show a certain degree of twisting of the bond connecting the meta‐cyclophane unit and the central π system due to steric crowding. UV spectra of 2 and 3 and of the charge‐transfer complexes [ 2 /TCNE] and [ 3 /TCNE] allow for a discussion of π‐π interaction between the central stilbene subunit and the outer benzene rings of the metacyclophane units. Bis[2.2]meta‐cyclophanes 2 and 3 reacted regioselectively with hexacar‐bonylchromium on the outer benzene rings giving 1:1 and 1:2 complexes 9–14 with tricarbonylchromium. No 1:3 and 1:4 complexes formed due to steric restrictions. Analysis of UV spectral data of the complexed [2.2]metacyclophanes was performed for an indication of π‐π interactions in the complexes.