Electrospray mass spectrometry beyond analytical chemistry: studies of organometallic catalysis in the gas phase

Electrospray tandem mass spectrometry, one of the most important techniques for the characterization of biological macromolecules, has become increasingly popular as an analytical tool in inorganic/organometallic chemistry. Going one step further, we have shown that the coupling of electrospray ionization to ion-molecule techniques in the gas phase can yield detailed information about elementary reaction steps of transition-metal compounds with fully intact coordination spheres. This method opens a door to the study of extremely reactive intermediates that have previously not been within reach of condensed-phase techniques. Moreover, working in the gas phase, information about the intrinsic reactivity of the complex itself is obtained, thus excluding solvent effects, aggregation phenomena etc. We have demonstrated the usefulness of this method for various important transition-metal mediated reactions such as C-H activation, oxidation, and olefin polymerization. Through the utilization of collision-induced dissociation (CID) threshold methodology, the quantitative measurement of thermochemical data for metal-ligand bond energies and elemental reaction steps is possible. In several instances, we have demonstrated that the CID threshold methodology can be applied to molecules with relatively many degrees of freedom, yielding experimental thermochemical data of high quality. Both the qualitative and quantitative reaction studies of organometallic intermediates will contribute to deepen our mechanistic understanding of important catalytic reactions. (C) 2001 Elsevier Science B.V.