Mono- and diferrocenyl complexes with electron-accepting moieties formed by the reaction of ferrocenylalkynes with tetra-cyanoethylene

Reaction of tetracyanoethylene with ethynylferrocene, diferrocenylacetylene, and diferrocenyldiacetylene in dichloromethane solution at room temperature produced 1:1 adducts of 2,5-dicyano-3-ferrocenylhexa-2,4-dienedinitrile (1), 2,5-dicyano-3,4-diferrocenylhexa-2,4-dienedinitrile (2), and 2,5-dicyano-3-ferrocenyl-4-ferrocenylethynylhexa-2,4-dienedinitrile (3), respectively, under mild conditions. X-ray structure determination of 1-3 showed that they exhibit s-cis-butadiene conformations in the solid state. Cyclic voltammograms showed that there are negligible electronic communications between the ferrocenyl moieties in 2 and 3, probably because of the highly twisted structures.