%0 Journal Article %T On the oxidation of dibenzo[fg,ij]pentaphene and dinaphtho[2,1,8,7-defg:2',1',8',7'-ijkl]pentaphene dianions %A IVAN GUTMAN %J Journal of the Serbian Chemical Society %D 1999 %I Serbian Chemical Society %X The dianion of dibenzoSfg,ijCpentaphene has recently been synthesized and shown to react with oxygen, forming the 15,16-dioxo derivative in nearly quantitative yield. Oxidation of the dianion of dinaphtho[2,1,8,7-defg:2',1',8',7'-ijkl]pentaphene under similar conditions does not result in any dioxo product. It is shown that these findings are a consequence of the different modes of cyclic conjugation in the two dianions. Cyclic conjugation in the mentioned two dianions, as well as in a number of other structurally related benzenoid dianions is assessed by means of a quantum-chemical method, developed earlier by the author. %K dianions %K benzenoid hydrocarbons %K cyclic conjugaiton %U http://www.shd.org.yu/HtDocs/SHD/Vol64/No10-Pdf/V64-no10-01.zip