Facile N[BOND]N Activation in Benzotriazole: Capturing the Dimroth Azo/Triazole Intermediate by Complexation to Iridium



The in situ observation of benzotriazole ring and ring-opened isomers, which result from the Dimroth equilibrium for 1-[(nonafluorobutane)sulfonyl]benzotriazole, 1, in solution by 19F NMR and UV/Vis spectroscopy is reported. Two benzotriazoles, compound 1 and 1,1′-sulfonylbis(benzotriazole) (3), undergo Dimroth triazole ring opening and coordination to an iridium(I) metal center to give either linear diazo [IrI1-NNPhNSO2C4F9)(Cl)(PPh3)2] (2) or an unusual double bent diazene [IrIII3-NNPhNSO2Btz)(Cl)(PPh3)2] (4; Btz=benzotriazole) complex.