Redetermination of biphenylene at 130K

Biphenylene is one of the key compounds in the discussion of bond localization in aromatic systems, usually addressed as the Mills-Nixon effect [Mills & Nixon (1930). J. Chem. Soc. p. 2510]. A pronounced bond localization due to the Mills-Nixon effect in the direction of one of the Kekule forms is established. Compared with the previous structure determination by Fawcett & Trotter [Acta Cryst. (1966), 20, 87-93], the significance of bond-length alternation in relation to the s.u.'s in the six-membered rings has been dramatically increased.

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