Synthesis of poly(arylene cobaltacyclopentadienylene)s, a new class of organometallic π-conjugated polymers, by metallacycling polymerization and their physical properties

Tadashi Shimura, Akira Ohkubo, Nao Matsuda, Isao Matsuoka, Kunitsugu Aramaki, Hiroshi Nishihara

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Reaction of Cp′Co(PPh3)2, where Cp′ = η5-cyclopentadienyl (Cp) or η5-n-hexylcyclopentadienyl (hexCp), with conjugated diacetylenes, RC≡C-A-C≡CR, where A = p-phenylene, p-fluorophenylene, p-2,5-difluorophenylene, or 4,4′-biphenylene and R = H or Me affords new organometallic polymers, [-C4R2{CoCp′(PPh3)}-A-]n (1-6) involving linearly π-conjugated chains. The polymers are insoluble when Cp′ = Cp but soluble in common organic solvents when Cp′ = hexCp. It is suggested by the results of reactions of (hexCp)Co(PPh3)2 with PhC≡CH and PhC≡CMe that stereoregularity favorable to π-conjugation, i.e., connection of cobaltacyclopentadienylene moieties at 2,5 position is higher when R = Me compared to when R = H. The cobaltacyclopentadiene polymers undergo quasi-reversible oxidation and irreversible reduction at low temperatures. The oxidation potential is not significantly changed, but the reduction potential shifts considerably in the positive direction for the polymers compared to monomeric cobaltacyclopentadienes. The polymers' bandgap energies (as estimated from visible spectra) are between 2.1 and 2.3 eV. Photoconductivity is observed for [-C4Me2{Co(hexCp)(PPh3)}-C6H 4-]n (6e).

Original languageEnglish
Pages (from-to)1307-1315
Number of pages9
JournalChemistry of Materials
Issue number6
Publication statusPublished - 1996 Jun


ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

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