TY - JOUR
T1 - Biphenylene dimer. Molecular fragment of a two-dimensional carbon net and double-stranded polymer
AU - Rajca, Andrzej
AU - Safronov, Andrej
AU - Rajca, Suchada
AU - Ross, Charles R.
AU - Stezowski, John J.
PY - 1996/8/7
Y1 - 1996/8/7
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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U2 - 10.1021/ja961065y
DO - 10.1021/ja961065y
M3 - Article
AN - SCOPUS:0029739928
SN - 0002-7863
VL - 118
SP - 7272
EP - 7279
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 31
ER -