Pyrenium cations

A systematic carbocation concentration dependency study on NMR chemical shifts was performed for the C-l-protonated 477-cyclopenta[fi e/ phenanthrenium cation 7H+ and the C-l-protonated pyrenium cation 2H+ (Fig. 11). Shielding of the PAH arenium ion protons and carbons was observed with decreasing FSO3H PAH ratios without noticeable line-broadening. This was attributed to cation-anion interactions in the low FSO3H PAH domain and possible formation of contact ion... 

The available data on chemical and physical properties of 72 and 73 are extremely limited and biological activity data are nonexistent. Thus, this study provided the first glance into their carbocations and oxidation dieations, while augmenting and reinforcing the previous stable ion data on the pyrenium cations. 

Figure 33 summarizes the NMR data for dihydropyrenium (ethanophenan-threnium) mono- and dications.25 The charge delocalization mode in the symmetrical dications is noteworthy. The pattern differs from that in parent pyrenium cation and its 2,7-di-tert-butyl-substituted derivatives. 

Fig. 34. H and 13C NMR chemical shifts for cyclobutene-fused pyrenium cations.

---