2,5-DIAZACYCLOPENTADIENYLIDENE: A STANDARD CARBENE OR A HIGHLY REACTIVE DIRADICAL?

Article abstract of DOI:10.1246/cl.1980.1489

2,5-Diazacyclopentadienylidene (2H-imidazolidene), generated either by photolysis or thermolysis from 2-diazo-2H-imidazole, reacts with benzene derivatives to give mainly a mixture of o-, m-, p-substitued 2-phenylimidazoles.The carbene shows a strong diradical character, in sharp contrast with the well-known behavior of cyclopentadienylidene.