Mass spectrometric studies of elusive molecules that contain an N+-X- bond

This review will be concerned with the gas phase chemistry of 1,2- and 1,3- dipolar systems that contain a carbon-nitrogen bond. Although most of these compounds are stable molecules under normal conditions, certain congeners are reactive species that cannot be prepared using conventional procedures. The isolation and observation of these elusive compounds therefore require appropriate experimental conditions such as those provided by the gas phas e of a mass spectrometer: In these experiments, the radical cations, corres ponding to the molecule under study, must be prepared via indirect procedur es, including dissociative electron ionization, on-line flash-vacuum pyroly sis-mass spectrometry, or ion-molecule reactions. Their characterization is mainly based on collisional activation and ion-molecule reactions. The for mation of the corresponding highly reactive neutrals is attempted by neutra lization-reionization mass spectrometry. This review presents more than one hundred different molecules together with their methods of preparation and the experiment used to identify them. (C) 2000 John Wiley & Sons, Inc.