Ferrocenyl substituted chlorostilbenes and butadienes

The readily accessible -chlorophosphonates (OCH2CMe2CH2O)P(O)CH(Cl) C6H4-4-R [1: R=Me (a), OMe (b), Cl (c), H (d)] react with ferrocenecarboxaldehyde in the presence of NaH [Horner–Wadsworth–Emmons reaction] to give good yields of ferrocenyl substituted chlorostilbenes. The novel bis ferrocenyl butadiene C5H5FeC5H4 CH CH C(CN)CHC5H4FeC5H5 (9) as well as the ferrocenyl 2-cyano-1,3-butadienes 4-R C6H4 CH CH C(CN) CHC5H4FeC5H5 [R=Me (10a), OMe (10b), Cl (10c)] have been obtained by using the new allylphosphonate (OCH2CMe2CH2O)P(O)CH2C(CN) CHC5H4FeC5H5 (8); the latter compound was prepared in good yields by the reaction of the Baylis–Hillman adduct, C5H5FeC5H4CH(OH)C(CN) CH2 (7), with the chlorophosphite (OCH2CMe2CH2O)PCl. The electrochemical behavior of the ferrocenyl compounds thus synthesized has been studied; two reversible one-electron processes are observed in the case of compound 9 suggesting a cooperative interaction between the two ferrocenyl residues. © 2001 Elsevier Science B.V. All rights reserved.