Ionic Isomer Distinction by Neutralization‐Reionization Mass Spectrometry (NRMS): Carbonic Acid Radical Cations, (HO)2CO˙⊕ versus (H2O/CO2)˙⊕ Clusters

Reactions between CO 2 , and H 2 O or the corresponding radical cations are easily investigated with the aid of mass spectrometry. Whereas CO 2 reacts with H 2 O to give the weakly bonded van der Waals cluster 1 , reaction of H 2 O .⊕ with CO 2 leads exclusively to the proton‐bridged isomer 2 .⊕ . Attempts with a mass spectrometer to prepare the so far unknown neutral cluster 2 from 2 .⊕ under neutralization/reionization conditions were unsuccessful. This is presumably a consequence of the considerable difference between the (calculated) bond lengths and bond angles in the two species 2 .⊕ and 2 . The formation of (HO) 2 CO was not observed under these conditions. equation image