Specific solvent effects on the intramolecular electron transfer reaction in a neutral ferrocene donor polychlorotriphenylmethyl acceptor radical with extended conjugation

The synthesis and the optical, magnetic and electrochemical properties of the ferrocenylbutynene substituted polychlorotriphenylmethyl radical 1 are reported. Radical 1 is prepared in a three step synthetic route starting with a Wittig reaction to yield (E,Z)-{4-[4-(bis(2,3,4,5,6-pentachlorophenyl)methyl)-2,3,5,6-tetra-chlorophenyl]but-3-en-1-ynyl}-ferrocene (1H) which is subsequently deprotonated to yield the corresponding anion K+(18-crown-6) [1]− and finally oxidized to (E)-4-[4-(ferrocenyl)but-3-yn-1-enyl]-2,3,5,6-tetrachlorophenyl-bis(2,3,4,5,6-pentachlorophenyl) methyl radical (1). Radical 1 exhibits a charge-transfer band transition in the near infrared region which is associated with an intramolecular electron transfer from the ferrocene unit (donor) to the radical unit (acceptor) of this dyad molecule; its solvatochromism is studied in detail. The X-ray crystal structure of [K+(18-crown-6)](E)-[4-[4-(ferrocenyl)but-3-yn-1-enyl]-2,3,5,6-tetrachlorophenyl-bis(2,3,4,5,6-pentachlorophenyl) methide] [1]− has been determined. This organic salt forms an interesting one-dimensional coordination polymer by the coordination of the K+ cation with chlorine atoms of the organic carbanion.

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