Oxidation of 3-amino-2-phenylindazole () or thermolysis of 3-azido-2-phenylindazole () gives 2-cyanoazobenzene () quantitatively; thermolysis or photolysis of 3-azido-2, 1- benzisothiazoles () induces similar ring opening to give the transient 2- cyanothionitrosobenzenes ().