(a) Solution IR spectra of free 1-azido-4-(tert-butyl)benzene (above, blue) and 3 (below, red) in benzene. (b) EPR spectrum of 3 in frozen toluene at 4 K (above, black) and its simulation (below, red); simulation parameters: S = 3/2, g1 = 2.4, g2 = 2.4, g3 = 2.4; A1(Co) = 0 MHz, A2(Co) = 600 MHz, A3(Co) = 200 MHz. (c) Mulliken spin-density plot calculated for 3.52