Face-to-face fixed ferrocenes. Synthesis and properties of 2,10-diferrocenyl- and 2,5,7,10-tetraferrocenyl-1,6-methano[10]annulenes

Abstract

2,10-Diferrocenyl- and 2,5,7,10-tetraferrocenyl-1,6-methano[10]annulenes, in which the ferrocene nuclei are held proximate and cofacial, have been synthesized by using the palladium-catalyzed cross-coupling reaction of ferrocenylzinc chloride with 2,10-dibromo- and 2,5,7,10-tetrabromo-1,6-methano[10]annulenes. The structures of the face-to-face fixed ferrocene systems were determined by X-ray analysis. Cyclic voltammetric measurements of diferrocenyl- and tetraferrocenyl-1,6-methano[10]annulenes show two and three redox waves, respectively, reflecting the through-space and through-bond interactions of the ferrocene nuclei.