Supramolecular Organization Based on van der Waals Forces: Syntheses and Solid State Structures of Isomeric [6.6]Cyclophanes with 2,5-Diselenahex-3-yne Bridges

The ortho, meta, and para isomers 4-6 of [6.6]cyclophanes with 2,5-diselenahex-3-yne bridges were synthesized by reacting the his (selenocyanatomethyl) benzene derivatives 8a-8c with the lithium salt of trimethylsilylethyne to yield 9a-9c, deprotection of which afforded the bis(ethynylselenylmethyl)benzenes 10a-10c. The condensation of the bis-lithium salts of 10a-10c with 8a-8c yielded the target compounds 4-6. X-ray investigations on single crystals of 4-6 revealed intermolecular Se center dot center dot center dot Se interactions which contribute significantly to the solid-state structures of these species, In the case of the orthocyclophane 4, we found short distances be-tween one Se-C C-Se unit of each molecule leading to a linear chain of orthocyclophane rings. In the metacyclophane, 5, the rings adopt a chair conformation and are piled on top of each other. The resulting molecular channels are connected with each other by intermolecular Se center dot center dot center dot Se interactions. For 6 also a chair conformation of the [6.6]paracyclophane unit was encountered. In the solid state the rings of 6 are connected by intermolecular Se center dot center dot center dot Se bridges. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)