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 increasi ngly popular as an analytical tool in inorganic/organometallic chemistry. G oing one step further, we have shown that the coupling of electrospray ioni zation to ion-molecule techniques in the gas phase can yield detailed infor mation about elementary reaction steps of transition-metal compounds with f ully 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, informa tion 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 media ted 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 i nstances, we have demonstrated that the CID threshold methodology can be ap plied to molecules with relatively many degrees of freedom, yielding experi mental thermochemical data of high quality. Both the qualitative and quanti tative reaction studies of organometallic intermediates will contribute to deepen our mechanistic understanding of important catalytic reactions. (C) 2001 Elsevier Science B.V.