Ferrocene is considered as an analogue of benzene. The aromatic elongation of benzene leads to the formation of polycyclic aromatic hydrocarbons (commonly known by acenes) that are being used as benchmark materials of organic electronics. However, aromatic conjugation of ferrocene and other metallocenes is still in its infancy. We are interested to investigate the stability of ferrocene-capped polycyclic aromatic hydrocarbons in order to study their suitability in organic electronics. Our approach is to introduce electron-withdrawing groups on the cyclopentadienyl (Cp)-fused aromatics so that electron-rich Fe(II) center makes stable complexes with them. The project involves the Friedel-Crafts acylation of ferrocene with organic anhydrides to give keto-carboxylic acid<b>s</b>. The ketonic reduction to methylene under Clemmensen conditions followed by ring-closing gives anthrone like complexes. We have attempted reductive aromatization of these anthrones to build pi-extended ligands. Although aromatic extension is possible, these complexes exhibit high reactivity with air. We are working on introducing electron-withdrawing groups on the <i>peri</i>-positions of ferrocenyl moiety to see if that helps to stabilitze the complexes. Synthesis, characterization, and spectral properties of the metallocenes will be discussed.

Methodologies to extend the pi conjugation in metallocenes

256th National Meeting (2018)

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