Probing onium ions and carbocations by desorption/ionization mass spectrometry: Crossing the threshold between fragile salts and gaseous intact cations and subsequent guest–host and cation–molecule cluster chemistry

The utility of desorption/ionization mass spectrometric (DI/MS) techniques in dealing with physical organic problems involving fragile onium salts and carbocation salts has been explored. The efficacy of these methods, especially when coupled to tandem mass spectrometry, goes much beyond the analytical aspects dealing with identity/purity determinations. For example, insight can be gained regarding the role of the counterion in subsequent cation decomposition pathways. Guest–host chemistry of onium ions and various hosts (crowns, calixarenes) can be probed. The decomposition chemistry of the resulting ion–molecule clusters can be studied. Examples of onium salts and carbocation salts that have been studied are few, probably because research in this area has been mainly a domain for analytical chemists. This paper calls attention to the possibilities for dealing with topical physical organic problems.