Beschreibung:
<jats:title>Abstract</jats:title><jats:p>A novel oxidation method for the synthesis of labile azo‐alkanes is reported. Matrix‐isolated 2,3‐naphthoquinodimethane is obtained by photolysis of 1,4‐dihydrobenzo[<jats:italic>g</jats:italic>]‐phthalazine in a rigid matrix (EPA glass) at 77 K and the electronic structure of its ground and lowest excited states is discussed. Nitrogen elimination from 1,4‐dihydronaphtho[1,8‐<jats:italic>de</jats:italic>][1,2]‐diazepine to yield acenaphthene occurs exclusively upon ππ* excitation while irradiation in the n‐π* absorption region induces <jats:italic>cis/trans</jats:italic> isomerization of the azo‐moiety. Neither ns flash nor low‐temperature photolysis provide evidence for the occurrence of 1,8‐naphthoquinodimethane as an intermediate in the formation of acenaphthene.</jats:p>