The matrix isolation of a variety of aromatic diradicals is described
in this report. Flash vacuum pyrolysis of terephthaloyl and isophthalo
yl diiodide produces E/Z mixtures of hexa-1,5-diyne-3-ene but no dehyd
robenzene. [2.2]Paracyclophanes are highly strained molecules and are
shown to be precursors of a variety of interesting diradicals, novel k
etenes, and unusual quinoid compounds. Photolysis of substituted quino
ne diazides provides access to m-dehydrophenols, and thus allows for t
he direct spectroscopic observation of a derivative of m-dehydrobenzen
e.