Gaseous Behavior Study Of Argentinated Phenyl-containing Compounds In ESI-MS

Electrospray ionization mass spectrometry has been widely used in exploration of the stabilities of organometallte intermediates, but also their reactivities in gas phase, by directly transferring from liquid phase to gas phase and maintaining the weak interaction between the metal cation and the rest part. With the growing interest in the use of silver reagents, which is tend to coordinate with π-electron or n-electron, it is of great interest to study whether the silver cation promotes the similar reactions in gas phase. In this dissertation, using typical.aromatics as model compounds, the fragmentations of protonated and argentianted one were both carried out. By comparing their mass spectra, the fragments from gaseous reaction were figured out and further explored, which specifically includes the following five parts:1.Different from the collisional activation of argentinated N-benzylaniline, which presents only the 1,2-elimination of AgH, the fragmentation of protonated one gives rise to the elimination of benzene. The benzene loss from the benzyl moiety is actually not the result of dissociative proton transfer (PT). In fact, benzyl cation transfer (BCT) from the nitrogen to the anilinic ring (ortho or para position) is the key step for benzene loss. Such dissociation occurs only after the benzyl group migrating from the site with the highest benzylation nucleophilicity (nitrogen) to a different one (ortho or para position of aromatic ring), which is described as dissociative benzyl cation transfer. Based on theoretical calculations, deuterium-labeling experiments and blocking experiments, the novel mechanism of dissociative benzyl cation transfer was systematically confirmed.2.The collisional activation of argentinated N-benzylbenzamides presents an intriguing formation of benzylsilver cation by using ESI-MS. The results from tandem mass spectrometry together with deuterium-labeling experiments and DFT calculationssuggest that the generation of benzylsilver cation lays in the nucleophilic attack on the α-hydrogen by carbonyl oxygen. The breakdown curve additionally proves the competition between AgOH loss and 1,2-elimination of AgH, while the relationship between nucleophilicity of carbonyl oxygen and the formation of benzylsilver cation is further consolidated by the study on substituent effect. Similar organosilver cations could be "synthesized" as well when the benzyl moiety of the model complex is replaced by furylmethyl, thienylmethyl, naphthylmethyl or 3-methyl-2-butenyl.3.Argentination promotes the cyclization of N-allylbenzamide in gas phase and leads to a rare elimination of AgOH and a reported AgH loss. The intriguing elimination of AgOH is certified as the consequence of intramolecular cyclization between terminal olefine and carbonyl carbon following proton transfer to carbonyl oxygen, rather than simple enolization of amide.4.1n collisional activation of argentinated N-arylmethyl-pyridin-2-ylmethanimine, a neutral molecule of AgNH2 is eliminated, which is quite different from the protonated one. Taking argentinated N-benzyl-pyridin-2-ylmethanimine for example, the proposition that the AgNH2 loss results from intramolecular arylmethyl-transfer combined with cyclodeamination is rationalized by deuterium labeling experiments, blocking experiments, and theoretical calculations, while one of the lost hydrogens is confirmed from the methylene and the other one is from the ortho position (relative to the ipso carbon) of the aryl ring. The structure of the final product ion from loss of AgNH2 was furthermore confirmed by multistage mass spectrometry.5.Nazarov cyclization and Oxo Diels-Alder reaction induced by the naked silver cation in the collisional activation of silver(I)/chalcone complexes, which lead to the final elimination of AgOH and AgH respectively. Based on deuterium-labeling experiments, the NC involving the phenyl ring of benzoyl moiety is resposible for the AgOH loss, while the ODR involving another ring of styryl moiety is in charge of the AgH loss. The eliminated hydrogen is from the respectively activated phenyl ring.While DFT calculations and the substituent effect were utilized to confirm the reaction mechanisms.In addition, the intrinsic connection between gaseous reactions and condensed reactions was briefly summarized, while the general fragmentation behavior of protonated or cationized compounds were reviewed.