Synthesis of ferrocene-based redox-active polymers via palladium-catalysed coupling reactions

Article abstract of DOI:10.1016/0022-328X(96)06159-1

1,1′-Difunctionalised ferrocenes Fe(C₅H₄Z)₂ [Z = 4-BrC₆H₄ (1), 4-BrC₆H₄CH₂C(O)-(4a), 4-BrC₆H₄CH=CH-(6a)] undergo cross-coupling reactions with the dizinc reagent (ClZnC₆H₄)₂COCH₂CHC(Me)O (2) to give a series of conjugated and non-conjugated aromatic poly(ferrocenes) with ferrocenediyl moieties as part of the polymer backbone. Similar products are obtained by Heck-arylation of 1,1′-divinylferrocene with diiodoarenes I-R-I (R = 1,4-C₆H₄, 1,1′-C₆H₄-C₆H₄, 2,5-C₄H₂S, 1,1′-C₆H₄OC₆H₄). The coupling products form orange to deep red solids, which are poorly soluble and oligomeric in most cases. Cyclic voltammetry measurements in dichloromethane solution give redox potentials close to the parent ferrocenes, with apparently very little interaction between the widely spaced iron centres.