A nanosecond time-resolved resonance Raman (ns-TR3) spectroscopic study of the reactions of the 2-fluorenylnitrenium ion with several CS-substituted guanosine derivatives is reported. The TR3 spectra show that the 2-fluorenylnitrenium ion reacts with the CS-substituted guanosine derivatives (C8-methylguanosine and C8-bromoguanosine) to produce C8 intermediates with the methyl and bromine moieties still attached to the intermediate species at the C8 position. The C8-bromoguano sine species was observed to be less reactive toward the 2-fluorenylnitrenium ion compared to the guanosine and C8-methylguanosine species. Comparison of the TR3 spectra to the results obtained from density functional theory calculations was used to characterize the C8 intermediates observed to learn more about their structure and properties. The implications of these results for the chemical reactivity of aryinitrenium ions toward substituted guanosine derivatives are briefly discussed.