Spontaneous disproportionation of NO2 (N2o4) by aromatic hydrocarbons. Formation of nitrosonium EDA complexes as chemical intermediates
Strong (orange/red) colourations resulting immediately upon the exposure of nitrogen dioxide and its equilibrium dimer (dinitrogen tetroxide) to various aromatic hydrocarbons (ArH) are shown to arise from the nitrosonium EDA or electron donor-acceptor complexes [ArH, NO+NO(Formula presented.)]. The latter exhibit diagnostic charge-transfer absorptions and characteristic N-O stretching bands in the UV-vis and IR spectra, respectively, that relate directly to ArH/NO+ interactions extant in the EDA complexes previously derived from the authentic nitrosonium salt, NO+PF(Formula presented.). Time-resolved picosecond spectroscopy establishes the charge-transfer excited state of [ArH, NO+NO(Formula presented.)] to be essentially identical to that from [ArH, NO+BF(Formula presented.)]. Furthermore, the same temporal decay of the spectral transients (ArH+•) from both systems indicates minimal ion-pairing effects of the counterions (NO(Formula presented.) and BF(Formula presented.)) on the kinetics of back electron transfer.
Bosch, E., and J. K. Kochi. "Spontaneous disproportionation of NO 2 (N 2 o 4) by aromatic hydrocarbons. Formation of nitrosonium EDA complexes as chemical intermediates." Research on chemical intermediates 19, no. 9 (1993): 811-828.
Research on Chemical Intermediates