Direct visual evidence for quinoidal charge delocalization in poly-p-phenylene cation radical
Recently, X-ray crystallographic evidence of quinoidal charge delocalization in poly-p-phenylene cation radicals was reported [Banerjee, M. et al., J. Am. Chem. Soc. 2007, 129, 8070]. In this paper, direct visual evidence for quinoidal charge delocalization in quaterphylene (QP) is shown with three-dimensional (31)) charge difference densities. It was revealed that the extra positive charge mainly