77406-15-6

Upstream product

• 108-88-3 toluene 
• 108-88-3 toluene radical cation 

Relevant academic research and scientific papers

Time-resolved charge-transfer spectroscopy of aromatic EDA complexes with nitrosonium. Inner-sphere mechanism for electron transfer in the isoergonic region

Photoinduced electron transfer in various 1:1 aromatic EDA complexes with nitrosonium by the direct laser-pulse (20-ps and 10-ns fwhm) excitation of the charge-transfer bands leads to the spontaneous generation of the redox pair Ar?+ and NO. Temporal relaxation by back electron transfer to regenerate the EDA complex [Ar,NO+] is measured by following the spectral decay of Ar?+ with the aid of time-resolved spectroscopy over the two separate time domains I and II. Picosecond kinetics (k1) are associated with the first-order collapse of the geminate ion radical [Ar?+,NO] by inner-sphere electron transfer back to the EDA complex - the relatively slow rates with k1 ～ 108 s-1 arising from driving forces that approach the isoergonic region, coupled with the rather high reorganization energy of nitric oxide. These allow effective competition from diffusive separation (ks) to form Ar?+ and NO as kinetically separate entities. Microsecond kinetics (kII) are thus associated with the second-order (back) electron transfer from the freely diffusing Ar?+ and NO. However, the comparison of the second-order rate constants calculated from Marcus theory shows that outer-sphere electron transfer is too slow to account for the experimental values of kII. The second-order process is unambiguously identified (by the use of the thermochemical cycle in Scheme IV) as the alternative, more circuitous inner-sphere pathway involving the (re)association (ka) of Ar?+ and NO to afford the cation radical pair [Ar?+,NO] followed by its collapse to the EDA complex. The general implications of inner-sphere complexes as reactive intermediates in electron transfer mechanisms in the isoergonic and endergonic regions are presented.

A comparison of the relative binding energie of H(+) and NO(+) to aromatic and haloaromatic bases by high pressure mass spectrometry

Proton transfer equilibria (B1H(+) + B2 B1 + B2H(+)) and NO(+) transfer equilibria (B1NO(+) + B2 B1 + B2NO(+)) have been studied for the following bases B, benzene, toluene, o-, m-, and p-xylene.NO(+) transfer equilibria for fluoro- and chlorobenzene have also been studied.Pulsed electron beam, high-pressure ion source mass spectrometry has been used to obtain the equilibrium constant K and hence the free energy changes ΔG0 and from van't Hoff plots, ΔH0 and ΔS0.Entropy changes are in general much smaller for NO(+) transfer than for H(+) transfer but the magnitude of the changes in the proton affinity and NO(+) affinity of toluene caused by a fluorine substituent is about the same, even though the absolute value of the proton affinity is greater by a factor of 4.The position of the F substituent on toluene has a marked effect on proton affinity but no effect on NO(+) affinity.The latter appears to be responsive only to the inductive effect.