Fig. 4.

Experimental and calculated mass spectral isotope profiles. A and C show spectra for [5+Na]⁺ and [5]⁺ produced using ROSO₂¹⁴NH₂; corresponding spectra using ROSO₂¹⁵NH₂ are shown in B and D. E and G show spectra for the overlapping isotope distributions of [6+Na]⁺/[8+Na]⁺ (calculated ratio of 1:2) and [6]⁺/[8]⁺ (calculated ratio of 7:1) for ROSO₂¹⁴NH₂. F shows overlapping signals of [6+Na]⁺/[8+Na]⁺ in CD₂Cl₂ (calculated [6+Na]⁺ to [8+Na]⁺ ratio of 3:1). H shows overlapping signals from [6]⁺ and [8]⁺ (1:7) using ROSO₂¹⁵NH₂. Signal intensities for the [6]⁺/[8]⁺ distributions (G and H) are very low. Therefore, for clarity, ion signals that were larger than the isotope signals from [6]⁺/[8]⁺ were subtracted, and the spectrum was normalized to the most intense signal from [6]⁺/[8]⁺. The complete mass spectra for G and H are shown in Fig. S5.