Cyclopropenyl cation – the simplest Huckelʹs aromatic molecule – and its cyclic methyl derivatives in Titanʹs upper atmosphere

The recent measurements by Cassini Ion Neutral Mass Spectrometer (INMS) showed the presence of numerous carbocations and shed light on their composition in Titanʹs upper atmosphere. The present research identifies an important class of ion-molecule reactions proceeding via carbocation collision complexes, and its implications in the chemistry of Titanʹs thermosphere and ionosphere. An analysis (based on the kinetics and dynamics of the elementary chemical processes identified) of the Cassini measurements reveals the mechanism of formation of the three-membered Huckel aromatic rings-Cyclopropenyl cation and its cyclic methyl derivatives. For carbocations, a nonclassical three-carbon-center two-electron-bond structure is no longer a controversial topic in chemistry literature. Emphasis has been placed on a future coordinated effort of state-of-the-art laboratory experiments, quantum-chemical calculations, and astronomical ALMA and JWST observations including planetary in situ measurements at millimeter and submillimeter wavelengths to elucidate the structure, energetics and dynamics of the compositions of carbocations detected by Cassini cationic mass spectrometry. The carbocation chemistry in Titanʹs upper atmosphere has a possible bearing on the organic chemistry and aromaticity in the atmosphere of primitive earth.