SPECTROSCOPIC AND KINETIC CHARACTERIZATION OF DIPHENYLDIAZOMETHANE RADICAL-ANION

Diphenyldiazomethane radical anion (Ph2CN2•-) has been generated by radiolytic reduction of diphenyldiazomethane (Ph2CN2) in both protic and aprotic solvents. The absolute kinetics of formation and reactivity of Ph2CN2•- were obtained by monitoring its transient absorption (λmax = 355-370 nm) following nanosecond pulse radiolysis. In isopropyl alcohol, reaction of the solvated electron with Ph2CN2 forms Ph2CN2•- (λmax = 355 nm), which subsequently protonates to form Ph2CN2H), as detected by a sharp absorption band at 330 nm. In aprotic solvents and in the absence of added quenchers, Ph2CN2•- decays primarily by pseudo-first-order reaction with Ph2CN2. With added weak organic acids protonation of Ph2CN2•- also occurs. Ph2CN2•- reacts with molecular oxygen with a near diffusion-controlled rate; however, it demonstrates no reactivity toward hydrogen atom donors, and no evidence of thermal loss of N2 to produce diphenylcarbene radical anion was observed. © 1990 American Chemical Society.