Biphenylene dimer. Molecular fragment of a two-dimensional carbon net and double-stranded polymer

Andrzej Rajca, Andrej Safronov, Suchada Rajca, Charles R. Ross, John J. Stezowski

Research output: Contribution to journalArticle

66 Citations (Scopus)

Abstract

Biphenylene dimers, which may be considered as 'macrocyclic' 2 x 2 fragments of net 1 and dimeric fragments of a double-stranded polymer, 5, are prepared. X-ray crystallography on two polymorphs of the dimer 9 reveals that its bond alternation is analogous to that in biphenylene; the tetraphenylene part of 9 has approximately C(2h) symmetry with a small dihedral angle (< 12°) between the benzene rings in the adjacent biphenylenes. Cyclic voltammetry of 9 gives two reversible waves corresponding to a radical anion and a dianion; the lithium and potassium salts of these anions, 9.-,M+ (M = Li, K) and 92-,2M+ (M = Li, K), were generated and characterized by ESR, NMR, and UV-vis spectroscopies. The spectral data for the dianions are compatible with classical structures; no evidence for 'in-plane aromaticity' is found. For polymer 5, a localized band and large density of states near the Fermi level are found, using extended Huckel theory calculations.

Original languageEnglish (US)
Pages (from-to)7272-7279
Number of pages8
JournalJournal of the American Chemical Society
Volume118
Issue number31
DOIs
StatePublished - Aug 7 1996

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Dimers
Anions
Polymers
Negative ions
Carbon
X ray crystallography
X Ray Crystallography
Dihedral angle
Benzene
Fermi level
Ultraviolet spectroscopy
Polymorphism
Lithium
Cyclic voltammetry
Paramagnetic resonance
Potassium
Spectrum Analysis
Salts
Nuclear magnetic resonance

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Biphenylene dimer. Molecular fragment of a two-dimensional carbon net and double-stranded polymer. / Rajca, Andrzej; Safronov, Andrej; Rajca, Suchada; Ross, Charles R.; Stezowski, John J.

In: Journal of the American Chemical Society, Vol. 118, No. 31, 07.08.1996, p. 7272-7279.

Research output: Contribution to journalArticle

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AU - Stezowski, John J.

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N2 - Biphenylene dimers, which may be considered as 'macrocyclic' 2 x 2 fragments of net 1 and dimeric fragments of a double-stranded polymer, 5, are prepared. X-ray crystallography on two polymorphs of the dimer 9 reveals that its bond alternation is analogous to that in biphenylene; the tetraphenylene part of 9 has approximately C(2h) symmetry with a small dihedral angle (< 12°) between the benzene rings in the adjacent biphenylenes. Cyclic voltammetry of 9 gives two reversible waves corresponding to a radical anion and a dianion; the lithium and potassium salts of these anions, 9.-,M+ (M = Li, K) and 92-,2M+ (M = Li, K), were generated and characterized by ESR, NMR, and UV-vis spectroscopies. The spectral data for the dianions are compatible with classical structures; no evidence for 'in-plane aromaticity' is found. For polymer 5, a localized band and large density of states near the Fermi level are found, using extended Huckel theory calculations.

AB - Biphenylene dimers, which may be considered as 'macrocyclic' 2 x 2 fragments of net 1 and dimeric fragments of a double-stranded polymer, 5, are prepared. X-ray crystallography on two polymorphs of the dimer 9 reveals that its bond alternation is analogous to that in biphenylene; the tetraphenylene part of 9 has approximately C(2h) symmetry with a small dihedral angle (< 12°) between the benzene rings in the adjacent biphenylenes. Cyclic voltammetry of 9 gives two reversible waves corresponding to a radical anion and a dianion; the lithium and potassium salts of these anions, 9.-,M+ (M = Li, K) and 92-,2M+ (M = Li, K), were generated and characterized by ESR, NMR, and UV-vis spectroscopies. The spectral data for the dianions are compatible with classical structures; no evidence for 'in-plane aromaticity' is found. For polymer 5, a localized band and large density of states near the Fermi level are found, using extended Huckel theory calculations.

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