OPTICAL AND ELECTRON SPIN RESONANCE STUDIES ON PHOTOLYZED AND RADIOLYZED TETRAPHENYLHYDRAZINE AND RELATED COMPOUNDS

Ultraviolet and γ irradiation of tetraphenylhydrazine in rigid matrices at 77°K induces the following modes of decomposition, respectively. (C6H5)2NN(C6+H5) 2 + hv→ 2(C6H5)2N· (C6H5)2NN(C6H5) 2 + e- → (C6H5)2N· + (C6H5)2N- The radical pair in the photolysis has a spin-spin interaction as manifested by esr spectra, but it is not responsible for the electronic absorption band in the near-infrared region, contrary to the proposal by Kommandeur, et al. Flash photolysis of tetraphenylhydrazine in benzene solution at room temperature yields the diphenyl nitrogen radical which disappears by second-order kinetics with a rate constant of 2.5 × 107 l. mol-1 sec-1. Diphenylhydrazine in γ-irradiated matrices undergoes the dissociative electron attachment (C6H5)2NNH2 + e- → (C6H5)2N- + ·NH2, while dicarbazyl captures an electron to form the anion radical. The anion is stable at 77°K but dissociates upon bleaching with visible light into a carbazyl radical and a carbazyl anion. The extinction coefficient at 77°K was estimated for the following intermediate species, (C6H5)2N·, (C6H5)2N-, dicarbazyl anion, and carbazyl radical.