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Chem. Listy 104, 361‒393 (2010) Amerika 2010GAS-PHASE CHEMISTRY AS A MECHANISTICTOOL FOR SOLUTION CHEMISTRY ANDCATALYSISDETLEF SCHRÖDERInstitute of Organic Chemistry and Biochemistry, Academyof Sciences of the Czech Republic, Flemingovo náměstí 2,166 10 Prague 6, Czech RepublicMass spectrometry (MS) has numerous applicationsranging from elemental 1 and molecular analysis 2 to various"omics" in biology 3 and applications in medicine 4 . Olympicgames, for example, nowadays involve not only sports but alot of mass spectrometry for advanced doping tests 5 . Thesuccess of MS is due to the unique combination of highsensitivity and low sample requirements. Due to itswidespread usage, mass spectrometry is continuouslygrowing and offers excellent employment opportunities forqualified researchers.Most analytical applications of MS evolve as a spin-offof fundamental studies situated at the interplay betweenphysical, organic, and inorganic chemistry. Massspectrometry, for example, requires the sample to be ionizedwhich in turn leads to the determination of ionizationenergies and proton affinities. Similarly, the fragmentation ofions provide bond energies for organic, inorganic, andorganometallic compounds which allow to understandchemical reactivity and predict particularly reactive species.A key advantage and simultaneously an important drawbackis that gas-phase methods determine molecular properties inthe absence of any "environment" (e.g. solvents, counter-ionsetc.). The measured properties are therefore intrinsic for thespecies under study. As such they provide profound insightinto concepts of chemical bonding and reactivity and allowdirect comparison with theory. In turn, however, the intrinsicproperties may only poorly correlate with bulk processes inwhich the environment is an inherent part of chemicalreactivity. Consequently, the results obtained in gas-phasemeasurements need to be "translated" for their use in appliedchemistry and several schemes for such conversions havebeen developed.the amount of oligonuclear uranium species sampled via MSusing electrospray ionization (ESI) increases with theconcentration of the uranyl salt. For this system, we couldestablish a quantitative correlation between the gas-phasedata and results from solution chemistry (Fig. 1), therebyallowing a direct connection between the situation in the gasphase and in the bulk.The second example deals with chemical reactivity 7 .Under anaerobic conditions, Cu(I) can bring about a twofoldC−S coupling of bisiminodisulfides in almost quantitativeyield (1 → 2 + 3; Fig. 2). ESI of the reaction solution yieldsan abundant signal of the copper(I) complex (1)Cu + . Whenthis species is mass selected and heated by collisions withhelium, it looses the neutral C−S coupling product 2 to affordthe second C−S coupling product as Cu(I) complex, (3)Cu + .The results demonstrate that the catalytic sequence can occurin the presence of a single copper atom and that no higherorderaggregates are required for a mechanistic rationale.Figure 2. Cu(I)-mediated C−S coupling in solution and in the gasphase. The inset shows the measured and the modeled isotopecluster of the ion (1)Cu +This work was supported by the Academy of Sciences of theCzech Republic (Z40550506) and the European ResearchCouncil (AdG HORIZOMS).Figure 1. Mono- and oligonuclear uranyl cations observed viaMS as a function concentration in solutionThe first example of such a "translation" concernssolutions of uranyl nitrate in water 6 . While seemingly trivial,REFERENCES1. Becker J. S., Jakubowski N.: Chem. Soc. Rev. 38, 1969(2009).2. Gross J. H.: Mass Spectrometry: A Textbook. Springer-Verlag, Heidelberg, Germany, 2004.3. James P.: Quart. Rev. Biophys. 30, 279 (1997).4. Spanel P., Smith D.: Mass Spectrom. Rev. 24, 661(2005).5. Hemmersbach P.: J. Mass Spectrom. 43, 839 (2008).6. Tsierkezos N. G., Roithová J., Schröder D., Ončák M.,Slavíček P.: Inorg. Chem. 48, 6287 (2009).7. Šrogl J., Hyvl J., Révész A., Schröder, D.: Chem.Commun. 3463 (2009).382