Electronic structure calculations on the methane catalyzed HCO+/HOC+ potential energy surface have been conducted. The results show that 1,2-proton transfer from C to O can be efficiently catalyzed by CH4. The complex CH4/HCO+ and the closely related species, CH5+/CO, are separated from the methoxymethyl cation CH3OCH2+ by a large potential energy barrier. It follows from the calculations that the metastable methoxymethyl cation is very unlikely to dissociate to yield HOC+. New experiments also show that HOC+ is not produced to any observable extent. A new explanation is proposed for the composite peak for m/z 29 observed from metastable dissociation of metastable methoxymethyl cation. The two components both arise from the formation of HCO+, but via different transition states. The minor, narrow, component involves dissociation from the CH5+/CO complex and the broad peak from the CH4/HCO+ ion–molecule complex.
BohmeD.K., “Proton-transport in the catalyzed gas-phase isomerization of protonated molecules”, Int. J. Mass Spectrom. Ion Processes24, 95 (1992).
2.
NobesR.H.RadomL., “HOC+: An Observable Interstellar Species? A Comparison With the Isomeric and Isoelectronic HCO+ HCN and HNC”, Chem. Phys.60, 1 (1981).
3.
YamaguchiY.RichardsC.A.JrSchaeferH.F.III, “High level ab initio study on the ground state potential energy hyper-surface of the HCO+-COH+ system”, J. Chem. Phys.101, 8945 (1994).
4.
HarlandP.W.KimN.D.PetrieS.A., “Kinetic and electron impact studies of the formyl/isoformyl (HCO+/COH+) isomers”, Aust. J. Chem.42, 9 (1989).
5.
FreemanC.G.KnightJ.S.LoveJ.G.McEwanM.J., “The reactivity of isoformyl ion (HOC+) and the proton affinity of carbon monoxide at oxygen”, Int. J. Mass Spectrom. Ion Processes80, 255 (1987).
6.
Wagner-RedekerW.KemperP.R.JarroldM.F.BowersM.T., “The formation and reactivity of HOC+: Interstellar implications”, J. Chem. Phys.83, 1121 (1985).
7.
(a) CollinsM.A.PetrieS.ChalkA.J.RadomL., “Protontransport catalysis and proton-abstraction reactions: An ab initio dynamical study of X+HOC+ and XH++CO(X=Ne, Ar, and Kr)”, J. Chem. Phys.112, 6625 (2000); (b) ChalkA.J.RadomL., “Proton-Transport Catalysis: A Systematic Study of the Rearrangement of the Isoformyl Cation to the Formyl Cation”, J. Am. Chem. Soc.119, 7573, (1997); (c) GauldJ. W.RadomL., “Effects of Neutral Bases on the Isomerization of Conventional Radical Cations CH3X+ to Their Distonic Isomers CH2XH+ (X=F, OH, NH2): Proton-Transport Catalysis and Other Mechanisms”, J. Am Chem. Soc.119, 9831 (1997); (d) GauldJ. W.AudierH.FosseyJ.RadomL., “Water-Catalyzed Interconversion of Conventional and Distonic Radical Cations: Methanol and Methyleneoxonium Radical Cations”, J. Am. Chem. Soc.118, 6299 (1996); (e) ChalkA.J.RadomL., “Ion-Transport Catalysis: Catalyzed Isomerizations of NNH+ and NNCH3+”, J. Am. Chem. Soc.121, 1574 (1999).
8.
CunjeA.RodriquezC.F.BohmeD.K.HopkinsonA.C., “Interconversion of ROC+ and RCO+ (R=H and CH3): Gas-Phase Catalysis by Argon and Dinitrogen”, J. Phys. Chem. A102, 478 (1998).
9.
FridgenT.D.ParnisJ.M., “A density functional theory study of the catalytic role of Ar, Kr, Xe, and N2 in the CH3OH-+ to CH2OH2-+ isomerization reaction”, Int. J. Mass Spectrom.190/191, 181 (1999).
10.
For example: (a) KnightJ.S.FreemanC.G.McEwanM.J., “Isomers of C2H4N+ and the proton affinities of acetonitrile and methyl isocyanide”, J. Am. Chem. Soc.108, 1404 (1986); (b) PetrieS.FreemanC.G.Meot-NerM.McEwanM.J.FergusonE.E., “Experimental study of HCN+ and HNC+ ion chemistry”, J. Am. Chem Soc.112, 7112 (1990); (c) AudierH.E.MilletA.LeblancD.MortonT.H., “Unimolecular decompositions of the radical cations of ethylene glycol and its monomethyl ether in the gas phase. Distonic ions versus ion-neutral complexes”, J. Am. Chem. Soc.114, 2020 (1992); (d) MourguesP.AudierH.E.LeblancD.HammerumS., “Bimolecular Reactions of Distonic Ions: Proton Transfer and Hydrogen Atom Abstraction with CH2OH2+”, Org. Mass. Spectrom.28, 1098 (1993); (e) AudierH.LeblancD.MourguesP.McMahonT.B.HammerumS.J., “Catalysed Isomerization of Simple Radical Cations in the Gas Phase”, Chem. Soc. Chem. Commun.2329 (1994); (f) ChouP.K.SmithR.L.ChyallL.J.DenttamaaH.I., “Reactivity of the Prototype Organosulfur Distonic Ion: CH2SH2+”, J. Am. Chem. Soc.117, 4374 (1995); (g) ZhangX.K.ParnisJ.M.LewarsE.G.MarchR.E., “FTIR spectroscopic investigation of matrix-isolated isomerization and decomposition products of ionized acetone: Generation and characterization of 1-propen-2-ol”, Can. J. Chem.75, 276 (1997).
11.
FergusonE.E., “Reactions of hydroxydiazonium (NNOH+) and diazenyloxoniumylidene (HNNO+) ions with methane and nitric oxide”, Chem. Phys. Lett.156, 319 (1989).
12.
MorpurgoS.BrahimiM.BossaM.MorpurgoG.O., “A theoretical study on proton transfer in the mutarotation of sugars”, Phys. Chem. Chem. Phys.2, 2707 (2000).
13.
(a) MourguesP.Chamot-RookeJ.van der RestG.NedevH.AudierH.E.McMahonT.B., “Catalyzed keto-enol tautomerism of ionized acetone: A Fourier transform ion cyclotron resonance mass spectrometry study of proton transport isomerization”, Int. J. Mass Spectrom.210/211, 429 (2001); (b) van der RestG.NedevH.Chamot-RookeJ.MourguesP.McMahonT.B.AudierH.E., “Proton-transport catalysis in the gas phase. Keto-enol isomerization of ionized acetaldehyde”, Int. J. Mass Spectrom.202, 161 (2000).
14.
(a) TrikoupisM.A.GerbauxP.LavoratoD.J.FlammangR.TerlouwJ.K., “Hydrogen-shift isomers of ionic and neutral hydroxypyridines: A combined experimental and computational investigation”, Int. J. Mass Spectrom.217, 97 (2002); (b) TrikoupisM.A.BurgersP.C.RuttinkP.J.A.TerlouwJ.K., “Benzonitrile assisted enolization of the acetone and acetamide radical cations: Proton-transport catalysis versus an intermolecular H+ transfer mechanism”, Int. J. Mass Spectrom.210/211, 489 (2001); (c) FellL.M.RuttinkP.J.A.TrikoupisM.A.TerlouwJ.K., “Dissociation chemistry of the hydrogen-bridged radical cation [CH2=O–H–O=C-CH3]+: Proton transport catalysis and charge transfer”, Int. J. Mass Spectrom.195/196, 85 (2000).
15.
TuY.-P.HolmesJ.L., “Selected Radical Removal from Proton-Bound Dimers. A Strategy for Studying Solvated Distonic Ions”, J. Am. Chem. Soc.122, 3695 (2000).
16.
AudierH.E.BouchouxG.McMahonT.B.MillietA.VulpiusT., “Methoxymethyl Cation [CH3OCH2]+ Revisited: Experimental and Theoretical Study”, Org. Mass Spectrom.29, 176 (1994).
17.
CurtissL.A.RedfernP.C.RaghavachariK.RassolovV.PopleJ.A., “Gaussian-3 theory using reduced Moller-Plesset order”, J. Chem. Phys.110, 4703 (1999).
18.
FrischM.J.TrucksG.W.SchlegelH.B.ScuseriaG.E.RobbM.A.CheesemanJ.R.ZakrzewskiV.G.MontgomeryJ.A.JrStratmannR.E.BurantJ.C.DapprichS.MillamJ.M.DanielsA.D.KudinK.N.StrainM.C.FarkasO.TomasiJ.BaroneV.CossiM.CammiR.MennucciB.PomelliC.AdamoC.CliffordS.OchterskiJ.PeterssonG.A.AyalaP.Y.CuiQ.MorokumaK.MalickD.K.RabuckA.D.RaghavachariK.ForesmanJ.B.CioslowskiJ.OrtizJ.V.BaboulA.G.StefanovB.B.LiuG.LiashenkoA.PiskorzP.KomaromiI.GompertsR.MartinR.L.FoxD.J.KeithT.Al-LahamM.A.PengC.Y.NanayakkaraA.GonzalezC.ChallacombeM.GillP.M.W.JohnsonB.ChenW.WongM.W.AndresJ.L.GonzalezC.Head-GordonM.ReplogleE.S.PopleJ.A., Gaussian 98, Revision A.7.Gaussian, Inc., Pittsburgh, PA, USA (1998).
19.
HolmesJ.L.MayerP.M., “A Combined Mass Spectrometric and Thermochemical Examination of the C2,H2,N Family of Cations and Radicals”, J. Phys. Chem. A.99, 1366 (1995).
20.
HiraokaK.KebarleP., “Determination of the stabilities of H5+, H7+, H9+, and H11+ from measurement of the gas phase ion equilibria Hn+ + H2 = Hn+2+ (n = 3,5,7,9)”, J. Chem. Phys.62, 2267 (1975).
21.
HiraokaK.KebarleP., “Stability and structure of H3CO+ formed from COH+ + H2 at low temperature”, J. Chem. Phys.63, 1688 (1975).
22.
DeFreesD.J.McLeanA.D.HerbstE., “Calculations Concerning the HCO+/HOC+ Abundance Ratio in Dense Interstellar Clouds”, The Astrophysical Journal279, 322 (1984).
23.
LiasS.G.BartmessJ.E.LiebmanJ.F.HolmesJ.L.LevinR.D.MallardW.G., “Gas-Phase Ion and Neutral Thermochemistry”, J. Phys. Chem. Ref. Data, Supp. 1. (1988).
24.
BurgersP.C.HolmesJ.L.MommersA.A., “Laboratory Experiments on the Interstellar Species [HCO]+ and [COH]+”, J. Am. Chem. Soc.107, 1099 (1985).
