Motivated by the search for ways of a more efficient usage of the large, unexploited resources of methane, recent progress in the gas-phase activation of methane by ligated transition-metal ions is discussed. Mass spectrometric experiments demonstrate that the ligands can crucially influence both reactivity and selectivity of transition-metal cations in bond-activation processes, and the most reactive species derive from combinations of transition metals with the electronegative elements fluorine, oxygen, and chlorine. Furthermore, the collected knowledge about intramolecular kinetic isotope effects associated with the activation of C-H(D) bonds of methane can be used to distinguish the nature of the bond activation as a mere hydrogen-abstraction, a metal-assisted mechanism or more complex reactions such as formation of insertion intermediates or sigma-bond metathesis.

Institute of Organic Chemistry and Biochemistry Academy of Sciences of the Czech Republic Flemingovo nám 2 16610 Prague Czech Republic

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Olah GA, Goeppert A, Prakash GKS. Beyond Oil and Gas: The Methanol Economy. Weinheim, Germany: Wiley–VCH; 2006. PubMed

Irikura KK, Beauchamp JL. Methane oligomerization in the gas phase by 3rd-row transition metal ions. J Am Chem Soc. 1991;113:2769–2770.

Irikura KK, Beauchamp JL. Electronic-structure considerations for methane activation by 3rd-row transition-metal ions. Phys Chem. 1991;95:8344–8351.

Wesendrup R, Schröder D, Schwarz H. Design and realization of a catalytic cycle for the Pt+ mediated oxidation of methane by molecular oxygen in the gas phase. Angew Chem Int Ed Engl. 1994;33:1174–1176.

Pavlov M, et al. Pt+-catalyzed oxidation of methane: Theory and experiment. J Phys Chem A. 1997;101:1567–1579.

Wesendrup R, Schwarz H. Tantalum-mediated coupling of methane and carbon dioxide in the gas phase. Angew Chem Int Ed Engl. 1995;34:2033–2035.

Sändig N, Koch W. A quantum chemical view on the mechanism of the Ta+-mediated coupling of carbon dioxide with methane. Organometallics. 1998;17:2344–2351.

Chiodo S. Activation of methane by the iron dimer cation. A theoretical study. J Phys Chem A. 2006;110:12501–12511. PubMed

Liu F, Zhang X-G, Armentrout PB. Activation of CH4 by gas-phase Ni+ and the thermochemistry of Ni-ligand complexes. Phys Chem Chem Phys. 2005;7:1054–1064. PubMed

Armentrout PB, Sievers MR. Activation of CH4 by gas-phase Zr+ and the thermochemistry of Zr-ligand complexes. J Phys Chem A. 2003;107:4396–4406. PubMed

Parke LG, Hinton CS, Armentrout PB. Why is hafnium so unreactive? Experimental and theoretical studies of the reaction of Hf+ with methane. Int J Mass Spectrom. 2006;254:168–182.

Armentrout PB. Activation of CH4 by gas-phase Mo+, and the thermochemistry of Mo-ligand complexes. J Phys Chem A. 2006;110:8327–8338. PubMed

Parke LG, Hinton CS, Armentrout PB. Experimental and theoretical studies of the activation of methane by Ta. J Phys Chem C. 2007;111:17773–17787.

Armentrout PB, Shin S, Liyanage R. Guided-ion beam and theoretical study of the potential energy surface for activation of methane by W+ J Phys Chem A. 2006;110:1242–1260. PubMed

Armentrout MM, Li F-X, Armentrout PB. Is spin conserved in heavy metal systems? Experimental and theoretical studies of the reaction of Re+ with methane. J Phys Chem A. 2004;108:9660–9672.

Li F-X, Zhang X-G, Armentrout PB. The most reactive third-row transition metal: Guided ion beam and theoretical studies of the activation of methane by Ir+ Int J Mass Spectrom. 2006;255/256:279–300.

Li F-X, Armentrout PB. Activation of methane by gold cations: Guided ion beam and theoretical studies. J Chem Phys. 2006;125 Art. No. 133114. PubMed

Roth LM, Freiser BS. Gas-phase chemistry and photochemistry of doubly charged transition-metal containing ions. Mass Spectrom Rev. 1991;10:303–328.

Mourges P, Ferhati A, McMahon TB, Ohanessian G. Activation of hydrocarbons by W+ in the gas phase. Organometallics. 1997;16:210–224.

Ranasinghe YA, MacMahon TJ, Freiser BS. Formation of thermodynamically stable dications in the gas-phase by thermal ion molecule reactions—Ta2+ and Zr2+ with small alkanes. J. Phys Chem. 1991;95:7721–7726.

Liyanage R, Zhang XG, Armentrout PB. Activation of methane by size-selected iron cluster cations, Fen+ (n = 2–15): Cluster-CHx (x = 0–3) bond energies and reaction mechanisms. J Chem Phys. 2001;115:9747–9763.

Liu F, Zhang XG, Liyanage R, Armentrout PB. Methane activation by nickel cluster cations, Nin+ (n = 2–16): Reaction mechanisms and thermochemistry of cluster-CHx (x = 0–3) complexes. J Chem Phys. 2004;121:10976–10990. PubMed

Schröder D, Eller K, Prüsse T, Schwarz H. Ligand-enhanced selectivity in the CH/CC bond activation of ketones by iron(I) ions in the gas phase. Organometallics. 1991;10:2052–2057.

Schröder D, Schwarz H. Ligand effects as a probe for remote C–H bond activation by metal cations in the gas phase. J Organomet Chem. 1995;504:123–138.

Tjelta BL, Armentrout PB. Ligand effects in C–H and C–C bond activation by gas-phase transition metal-ligand complexes. J Am Chem Soc. 1996;118:9652–9660.

Albert G, et al. Methane activation by rhodium cluster argon complexes. Chem Phys Lett. 1997;268:235–244.

Achatz U, et al. The platinum hydride–methyl complex: A frozen reaction intermediate? J Phys Chem A. 1999;103:8200–8206.

Hertwig RH, et al. A comparative computational study of cationic coinage metal–ethylene complexes (C2H4)M+ (M = Cu, Ag, Au) J Phys Chem. 1996;100:12253–12260.

Schlangen M, Schröder D, Schwarz H. Pronounced ligand effects on the nickel-mediated thermal activation of methane. Angew Chem Int Ed. 2007;46:1641–1644. PubMed

Schlangen M, Schwarz H, Schröder D. Specific processes and scrambling in the dehydrogenation of ethane and the degenerate hydrogen exchange in the gas-phase ion chemistry of the Ni(C,H3,O)+/C2H6 couple. Helv Chim Acta. 2007;90:847–853.

Schröder D, Fiedler A, Schwarz J, Schwarz H. Generation and stabilities of anionic, neutral, and cationic [Fe,O2] complexes. Inorg Chem. 1994;33:5094–5100.

Schröder D, Fiedler A, Herrmann WA, Schwarz H. Coordination of dioxygen in three representative transition-metal cations FeO2+, CrO2+, and CH3Re(O2)2O+ Angew Chem Int Ed Engl. 1995;34:2517–2520.

Fiedler A, Kretzschmar I, Schröder D, Schwarz H. Chromium dioxide cation CrO2+ in the gas phase: Structure, electronic states, and the reactivity with hydrogen and hydrocarbons. J Am Chem Soc. 1996;118:9941–9952.

Beyer MK, et al. Corroding the chromium cation. Mol Phys Chem. 2001;99:699–702.

Schröder D, Diefenbach M, Klapötke TM, Schwarz H. UF3+—A thermochemically stable diatomic trication with a covalent bond. Angew Chem Int Ed Engl. 1999;38:137–140.

Mandich ML, Steigerwald ML, Reents WD. The effects of chloro substitution on the electronic-structure of ClCr+, ClMn+, and ClFe+ and their reactivity with small alkanes. J Am Chem Soc. 1986;108:6197–6202.

Mazurek U, Schröder D, Schwarz H. Generation and reactivity of chromium fluoride cations (CrFn+, n = 0–4) in the gas phase. Coll Czech Chem Comm. 1998;63:1498–1512.

Roithová J, Schröder D. Bimolecular reactions of molecular dications: New reactivity paradigms and bond-forming processes. Phys Chem Chem Phys. 2007;9:2341–2349. PubMed

Schröder D, Hrušák J, Schwarz H. Ligand effects on the reactivity of iron (II) cations FeX+ in the gas phase. Ber Bunsenges Phys Chem. 1993;97:1085–1090.

Schlangen M, Schwarz H, Schröder D. Ligand- and substrate effects in gas-phase reactions of NiX+/RH Couples (X = F, Cl, Br, I; R = CH3, C2H5, n-C3H7, n-C4H9) Chem Eur J. 2007;13:6810–6816. PubMed

Schröder D, Schwarz H. Activation of methane by gaseous platinum(II) ions PtX+ (X = H, Cl, Br, CHO) Can J Chem. 2005;83:1936–1940.

Carlin TJ, Sallans L, Cassady CJ, Jacobson DB, Freiser BS. Gas-phase reactions of group-8 metal hydride ions (FeD+, CoD+, and NiD+) with hydrocarbons. J Am Chem Soc. 1983;105:6320–6321.

Halle LF, Klein FS, Beauchamp JL. Properties and reactions of organometallic fragments in the gas phase—Ion-beam studies of FeH+ J Am Chem Soc. 1984;106:2543–2549. 1984.

Zhang Q, Bowers MT. Activation of methane by MH+ (M = Fe, Co, and Ni): A combined mass spectrometric and DFT study. J Phys Chem A. 2004;108:9755–9761.

Schlangen M, Schwarz H. Thermal activation of methane by group 10 metal hydrides MH+: The same and not the same. Angew Chem Int Ed Engl. 2007;46:5614–5617. PubMed

Schröder D, Schwarz H. C–H and C–C bond activation by ionic transition-metal oxides in the gas phase. Angew Chem Int Ed Engl. 1995;34:1973–1995.

Schröder D, Shaik S, Schwarz H. Characterization, orbital description, and reactivity patterns of transition-metal oxo species in the gas phase. Struct Bond. 2000;97:91–123.

Schröder D, Schwarz H. Intrinsic mechanisms of oxidation reactions as revealed by gas-phase experiments. Top Organomet Chem. 2007;22:1–15.

Schröder D, Shaik S, Schwarz H. Intrinsic mechanisms of oxidation reactions as revealed by gas-phase experiments. Acc Chem Res. 2000;33:139–145. PubMed

Shaik S, Hirao H, Kumar D. Reactivity of high-valent iron-oxo species in enzymes and synthetic reagents: A tale of many states. Acc Chem Res. 2007;40:532–542. PubMed

Ryan MF, Fiedler A, Schröder D, Schwarz H. Radical-like behavior of manganese oxide cation in its gas-phase reactions with dihydrogen and alkanes. J Am Chem Soc. 1995;117:2033–2040.

Schröder D, Schwarz H. FeO+ activates methane. Angew Chem Int Ed Engl. 1990;29:1433–1434.

Schröder D, et al. Activation of hydrogen and methane by thermalized FeO+ in the gas phase as studied by multiple mass-spectrometric techniques. Int J Mass Spectrom Ion Processes. 1997;161:175–191.

Schröder D, Fiedler A, Ryan MF, Schwarz H. Surprisingly low reactivity of bare FeO+ in its spin-allowed, highly exothermic reaction with molecular hydrogen to generate Fe+ and water. J Phys Chem. 1994;98:68–70.

Irikura KK, Beauchamp JL. Osmium-tetroxide and its fragment ions in the gas phase—Reactivity with hydrocarbons and small molecules. J Am Chem Soc. 1989;111:75–85.

Zhang GB, Li SH, Jiang YS. Density functional study on the mechanisms of the reactions of gas-phase OsOn+ (n = 1–4) with methane. Organometallics. 2004;23:3656–3667.

Schwarz H. Relativistic effects in gas-phase ion chemistry: An experimentalist's view. Angew Chem Int Ed Engl. 2003;42:4442–4454. PubMed

Rivalta I, Russo N, Sicilia E. Methane activation by chromium oxide cations in the gas phase: A theoretical study. J Comp Chem. 2006;27:174–187. PubMed

Schröder D, Schwarz H. Oxidations of alkanes by [Fe(O)OH]+ in the gas phase—the role of iron oxidation state in C–H activations. Angew Chem Int Ed Engl. 1991;30:991–993.

Kretzschmar I, Fiedler A, Harvey JN, Schröder D, Schwarz H. Effects of sequential ligation of molybdenum cation by chalcogenides on electronic structures and gas-phase reactivity. J Phys Chem A. 1997;101:6252–6264.

Brönstrup M, Schröder D, Kretzschmar I, Schwarz H, Harvey JN. Platinum dioxide cation: Easy to generate experimentally but difficult to describe theoretically. J Am Chem Soc. 2001;123:142–147. PubMed

Schröder D, Roithová J. Thermal activation of methane by MgO+ cations: It also works without a transition metal! Angew Chem Int Ed. 2006;45:5705–5708. PubMed

Brönstrup M, Kretzschmar I, Schröder D, Schwarz H. Iron-mediated amination of hydrocarbons in the gas phase. Helv Chim Acta. 1998;81:2348–2369.

Schröder D, Hrušák J, Schwarz H. Generation of bare FeF+ by C–F activation in the gas phase and evaluation of thermochemical data. Helv Chim Acta. 1992;75:2215–2218.

Schröder D, Schwarz H. Benzene oxidation by “bare” FeO+ in the gas phase. Helv Chim Acta. 1992;75:1281–1286.

Becker H, Schröder D, Zummack W, Schwarz H. Generation, fragmentation and interconversion processes of [Fe,C6,H6,O]+ isomers relevant for the oxygenation of aromatic hydrocarbons. J Am Chem Soc. 1994;116:1096–1100.

Stöckigt D, Schwarz H. Catalytic gas-phase oxidation of olefins mediated by Fe(C6H6)+ and a comparison of Fe(L)+ complexes (L = benzene, pyridine, naphthalene) Liebigs Ann. 1995:429–431.

Schröder D, Holthausen MC, Schwarz H. Radical-like activation of alkanes by the ligated copper-oxide cation (phen)CuO+ J Phys Chem B. 2004;108:14407–14416.

Butschke B, Schlangen M, Schwarz H, Schröder D. C–H bond activation of methane with gaseous [(CH3)Pt(L)]+ complexes (L = pyridine, bipyridine, and phenanthroline) Z Naturf B. 2007;62b:309–313.

Schröder D, Schwarz H. Fe+-catalyzed gas-phase oxidation of ethane by N2O. Angew Chem Int Ed Engl. 1990;29:1431–1433. 1990.

Schröder D, Brown R, Schwerdtfeger P, Schwarz H. Kinetics of radiative/termolecular associations in the low pressure regime: Reactions of bare Au+ with benzene. Int J Mass Spectrom. 2000;203:155–163.

Schröder D, Schwarz H, Aliaga-Alcalde N, Neese F. Fragmentation of the (cyclam-acetato) iron-azide cation in the gas phase. Eur J Inorg Chem. 2007;6:816–821.

Aliaga-Alcalde N, et al. The geometric and electronic structure of [(cyclam-acetato)Fe(N)+]: A genuine iron(V) species with a ground-state spin S = 1/2. Angew Chem Int Ed. 2005;44:2908–2912. PubMed

Schlangen M, et al. Gas phase C–H and N–H bond activation by a high valent nitrido-iron dication and [Image: see text] NH [Image: see text]-transfer to activated olefins. J Am Chem Soc. 2008;130:4285–4294. PubMed

Feyel S, Döbler J, Schröder D, Sauer J, Schwarz H. Thermal methane activation by tetranuclear V4O10+: From a “Holy Grail” to an achievable goal? Angew Chem Int Ed. 2006;45:4681–4685. PubMed

Feyel S, et al. Activation of methane by oligomeric (Al2O3)x+ (x = 3, 4, 5): The role of oxygen-centered radicals in thermal hydrogen-atom abstraction. Angew Chem Int Ed. 2008;47:1946–1950. PubMed

Schröder D, et al. Equilibrium isotope effects in cationic transition-metal(I) ethene complexes M(C2X4)+ with M = Cu, Ag, Au and X = H, D. Organometallics. 2000;19:2608–2615.

Derrick PJ. Isotope Effects in Fragmentation. Mass Spectrom Rev. 1985;2:285–298.

Heinemann C, Wesendrup R, Schwarz H. Pt+-mediated activation of methane—Theory and experiment. Chem Phys Lett. 1995;239:75–83. 1995.

Saueressig G, et al. Carbon 13 and D kinetic isotope effects in the reactions of CH4 with O(D-1) and OH: New laboratory measurements and their implications for the isotopic composition of stratospheric methane. J Geophys Res Atmos. 2001;106:23127–23138.

Shiota Y, Yoshizawa K. Methane-to-methanol conversion by first-row transition-metal oxide ions: ScO+, TiO+, VO+, CrO+, MnO+, FeO+, CoO+, NiO+, and CuO+ J Am Chem Soc. 2000;122:12317–12326.

Schröder D, Fiedler A, Hrušák J, Schwarz H. Experimental and theoretical studies towards a characterization of conceivable intermediates involved in the gas-phase oxid methane by bare FeO+. Generation of four distinguishable [Fe,C,H4,O]+ isomers. J Am Chem Soc. 1992;114:1215–1222.

Aguirre F, Husband J, Thompson CJ, Stringer KL, Metz RB. Electronic spectroscopy of intermediates involved in the conversion of methane to methanol by FeO+ J Chem Phys. 2002;116:4071–4078.

Shiota Y, Yoshizawa K. A spin-orbit coupling study on the spin inversion processes in the direct methane-to-methanol conversion by FeO+ J Chem Phys. 2003;118:5872–5879.

Schwarz H. On the spin-forbiddeness of gas-phase ion–molecule reactions: A fruitful intersection of experimental and computational studies. Int J Mass Spectrom. 2004;237:75–105.

Harvey JN, Poli R, Smith KM. Understanding the reactivity of transition metal complexes involving multiple spin states. Coord Chem Rev. 2003;238:347–361.

Böhme DK, Schwarz H. Gas-phase catalysis by atomic and cluster metal ions: The ultimate single-site catalysts. Angew Chem Int Ed. 2005;44:2336–2354. PubMed

Shilov AE. Activation of Saturated Hydrocarbons by Transition Metal Complexes. Dordrecht, The Netherlands: Reidel; 1984.

Periana RA, et al. Platinum catalysts for the high-yield oxidation of methane to a methanol derivative. Science. 1998;280:560–564. PubMed

Labinger JA, Bercaw JE. Understanding and exploiting C–H bond activation. Nature. 2002;417:507–514. PubMed

Labinger JA. Selective alkane oxidation: Hot and cold approaches to a hot problem. J Mol Catal. 2004;220:27–35.

Lersch M, Tilset M. Mechanistic aspects of C–H activation by Pt complexes. Chem Rev. 2005;105:2471–2526. PubMed

M-O Bonding Beyond the Oxo Wall: Spectroscopy and Reactivity of Cobalt(III)-Oxyl and Cobalt(III)-Oxo Complexes

Spectroscopic Characterization and Reactivity of Triplet and Quintet Iron(IV) Oxo Complexes in the Gas Phase