FACE-TO-FACE FIXED FERROCENES - SYNTHESIS AND PROPERTIES OF 2,10-DIFERROCENYL-1,6-METHANO[10]ANNULENE AND 2,5,7,10-TETRAFERROCENYL-1,6-METHANO[10]ANNULENE

2,10-Difenocenyl- and 2,5,7,10-tetraferrocenyl-1,6-methano[10]annulene s, in which the ferrocene nuclei are held proximate and cofacial, have been synthesized by using the palladium-catalyzed cross-coupling reac tion of ferrocenylzinc chloride with 2,10-dibromo- and 2,5,7,10-tetrab romo-1,6-methano[10]annulenes. The structures of the face-to-face fixe d ferrocene systems were determined by X-ray analysis. Cyclic voltamme tric 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. (C) 1998 Elsevier Science S.A. All rights reserved.