Cyclopentadienyl cations

Abstract

This perspective covers the chemistry of cyclopentadienyl cations from the first synthetic attempts generating transient variants to their successful isolation earlier this year. They are highly reactive species that researchers struggled to isolate and characterize that stifled efforts to explore their reactivity. The recent isolation of a cyclopentadienyl cation enabled characterization and reactivity studies that make this an exciting time in the area that will undoubtedly inspire research in cyclic four π–electron systems.