New heterocyclic dianions: n.m.r. characterization of 1,3-diphenylbenzo[c]-thiophene dianion, a stable 4n? charged system containing sulphur

1,3-Diphenylbenzo[c]thiophene dianion, (1)2– a member of the novel series of 4nπ polyheterocyclic dianions, has been prepared and characterized by n.m.r.; it shows a high stability and a peculiar charge distribution pattern in which the sulphur atom polarizes the charge towards the α-positions.