Sir: Despite rather extensive investigation of the chemistry of X5-phosphabenzenes l, 1.2 the question whether these structures possess appreciable aromatic stabilization (1') or whether they are better represented as delocalized ylides (l", l"', 1"") remains open. The basicity of the ring-unsubstituted 1, l-diphenyl-As-phosphabenzene la, prepared by a rather laborious route, suggests an ylide type of b~ nding.~ Unfortunately, data are limited and no NMR ...
