Short nonbond and long C-C bond in naphthalene-1,8-diylbis(10-methylacridinium) and the corresponding hexaphenylethane derivative: a new electrochromic pair exhibiting dynamic redox properties

The extremely long C-C bond [1.696(3) Angstrom] in the colorless dispiroacenaphthene-type hexaphenylethane is cleaved readily upon electrochemical transformation into the orange colored naphthalene-1,8-diylbis(acridinium), in which the two cationic units are forced to overlap in a face-to-face manner exhibiting the shortest C+...C+ interatomic contact of 2.927(7) Angstrom among the values ever reported. (C) 2004 Elsevier Ltd. All rights reserved.