Mechanism Elucidation of Organometallic Reactions

Because of the important catalytic role of some organometallic compounds in synthetic and biological processes, the study of metal ions and ionic transition metal compounds as well as their reactivities started more than 30 years ago [188-193]. Such have been the advances in ion/molecule reaction techniques that it has been possible to study single, elementary reaction steps or catalytic cycles mediated by transition metal ions on both the qualitative and quantitative level [189, 194-196). 

ESI has proven to be a most convenient means to transfer typical organometallics from solution to the gas phase, especially when the species of interest is present in the ionic form in solution. The first study of using ESI-MS for the analysis of ionic transition-metal complexes was made by Chait in 1994 [200], in which intact principal ions for ruthenium(II) dipyridyl complexes was observed. This represents the beginning of mass spectrometric characterization of known and defined solution-phase organometallic species [201-204]. Since its development, ESI-MS has been most elaborated for the ionization of large biomolecules such as proteins as a biochemical tool. However, when coupled with ion/molecule reactions and tandem mass spectrometry, ESI-MS is rapidly becoming the technique of choice for solution 

As a result, ESI-MS is ideal for the rapid screening of microscale reactions (thus minimizing wastage) and directing subsequent synthetic chemistry on the macroscopic scale [205]. The high sensitivity, the rapid analysis speed, and the capability to provide structural information on intermediates makes ESI-MS an excellent tool complementary and sometimes superior to electrochemistry and NMR for reaction mechanism investigation. 

Year Research Croups Reaction description and discovery 

Detection of transient ionic intermediates in the [241] Wittig, Mitsunobu, and Staudinger reactions directly from solution 

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