Ion–molecule reactions involving methyl isocyanide and methyl cyanide have been performed in a new rf-only hexapole collision cell inserted in a large-scale tandem mass spectrometer. Beside protonation processes, N-methyl cyanogen ions (CH3N+CCN) and 1-methyleneiminium-1-ethylenium ions (CH2CN+CH2) have been produced in high yield and fully characterized by high-energy collisional activation. The unimolecular chemistry of the molecular ions of caffeine (1,3,7-trimethyl xanthine) has been revisited on the basis of these new results.
HammerumS., “Distonic radical cations in gaseous and condensed phase”, Mass Spectrom. Rev.7, 123 (1988). doi: 10.1002/mas.1280070202
2.
TomazelaD.M.SabinoA.A.SparrapanR.GozzoF.C.EberlinM.N., “Distonoid ions”, J. Am. Soc. Mass Spectrom.17, 1014 (2006). doi: 10.1016/j.jasms.2006.03.008
3.
LiasS.G.BartmessJ.E.LiebmannJ.F.HolmesJ.L.LevinR.D.MallardW.G., “Gas phase ion and neutral thermochemistry”, J. Phys. Chem. Ref. Data17, Supplement 1 (1998).
4.
WheastR.C. (Ed.), Handbook of chemistry and physics, CRC Press, Boca Raton Florida, USA57th edition.
5.
DechampsN.FlammangR.BoulvinM.LamoteL.GerbauxP.NamP.C.NguyenM.T., “Ion/molelcule reactions involving ionized toluene or ionized methyl benzoate and neutral methyl isocyanide”, Int. J. Mass Spectrom., in press.
6.
DechampsN.FlammangR.GerbauxP.NamPC.NguyenM.T., “Characterization of a distonic isomer C6H5C+(OH)OCH2• of methyl benzoate radical cation by associative ion/molelcule reactions”, Int. J. Mass Spectrom.249/250, 484 (2006). doi: 10.1016/j.ijms.2005.10.014
7.
ErvastiH.K.JobstK.J.BurgersP.C.RuttinckP.J.A.TerlouwJ.K., “The acrylonitrile dimer ion: A study of its dissociation via self-catalysis, self-protonation and cyclisation into the pyrimidine radical cation”, Int. J. Mass Spectrom.262, 88 (2007). doi: 10.1016/j.ijms.2006.10.013
8.
BatemanR.H.BrownJ.LefevereM.FlammangR.Van HaverbekeY., “Applicaion in gaseous and neutral chemistry using a six-sector mass spectrometer”, Int. J. Mass Spectrom. Ion Processes115, 205 (1992). doi: 10.1016/0168-1176(92)85042-X
9.
FlammangR.Van HaverbekeY.BraybrookC.BrownJ., “A new hybrid mass spectrometer for the investigation of ion/molelcule reactions”, Rapid Commun. Mass Spectrom.9, 795 (1995). doi: 10.1002/rcm.1290090916
10.
RameshV.ReddyP. NagiSrikanthR.BhanuphrakashK.SrinivasR.FlammangR.DechampsN.GerbauxP., “C2H2S radical cations: Application of tandem mass spectrometry methodologies”, Int. J. Mass Spectrom.263, 289 (2007). doi: 10.1016/j.ijms.2007.03.007
FrischM.J.TrucksG.W.SchlegelH.B.ScuseriaG.E.RobbM.A.CheesemanJ.R.ZakrzewskiV.G.MontgomeryJ.A.StratmannR.E.BurantJ.C.DapprichS.MillamJ.M.DanielsA.D.KudinK.N.StrainM.C.FarkasO.TomasiJ.BaroneV.CossiM.CammiR.MennucciB.PomelliC.AdamoC.CliffordF.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.JohnsonB.ChenW.WongM.W.AndresJ.L.GonzalezC.Head-GordonM.RepogleE.S.PopleJ.A., Gaussian 98, Revision A.6.Gaussian Inc.; Pittsburgh, PA, USA (1998).
13.
WincelH.FokkensR.H.NibberingN.M.M., “On the rearrangement of the cyanomethyl cation from gaseous acetonitrile”, Int. J. Mass Spectrom. Ion Processes96, 321(1990). doi: 10.1016/0168-1176(90)85132-L
14.
MaquestiauA.Van HaverbekeY.FlammangR.MeyrantP., “Chemical ionization of some aromatic and aliphatic oximes”, Org. Mass Spectrom.15, 80 (1980). doi: 10.1002/oms.1210150206
15.
HeermaW.SarneelM.DijkstraG., “Structure and formation of gaseous [C3H4N]+ ions”, Org. Mass Spectrom.21, 681 (1986). doi: 10.1002/oms.1210211013
16.
See for instance: LawrenceP.BrennaJ.T., “Acetonitrile covalent adduct chemical ionization mass spectrometry for double bond localization in non-methylene-interrupted polyene fatty acid methyl esters”, Anal. Chem.78, 1312 (2006). doi: 10.1021/ac0516584
17.
GrayG.A., “Study of ion/molelcule reactions and reaction mechanisms in acetonitrile by ion cyclotron resonance”, J. Am. Chem. Soc.90, 6002 (1968). doi: 10.1021/ja01024a011
18.
KoputJ., “Ab initio heat of formation and singlet-triplet splitting for cyanocarbene (HCCN) and isocyanocarbene (HCNC)”, J. Phys. Chem. A107, 4717 (2003). doi: 10.1021/jp027774h
19.
(a) PoutsmaJ.C.UpshawS.D.SquiresR.R.WentholdP.G., “Absolute heat of formation and singlet-triplet splitting for HCCN”, J. Phys. Chem. A106, (2002) 1067 (2002); doi: 10.1021/jp013653q (b) NimlosM.R.DavicoG.GeiseC.M.WentholdP.G.LinebergerW.C.BlanksbyS.J.HadadC.M.PeterssonG.A.EllisonG.B., “Photoelectron spectroscopy of HCCN– and HCNC reveals the quasilinear triplet carbenes, HCCN and HCNC”, J. Chem. Phys.117, 4323 (2002). doi: 10.1063/1.1496473
20.
(a) KenaniA.BernierJ-L.HenichartJ-P., “Synthesis and EIMS fragmentation of [1,3-15N2] xanthine and [1,3-15N2]caffeine”, J. Label. Comp. Rad.36, 187 (1987); (b) GhilainV., “Identification de molécules organiques réactives en spectrométrie de masse par neutralisation-réionisation”, PhD Thesis, University of Mons-Hainaut, Belgium (1996).
21.
GerbauxP.FlammangR.NguyenM.T.SalpinJ.Y.BouchouxG., “Formation and cheracterization of acetonitrile N-methylide and N-methylketenimine radical cations in the gas phase”, J. Phys. Chem. A102, 861 (1998). doi: 10.1021/jp9724129
FlammangR.Van HaverbekeY.LaurentS.Barbieux-FlammangM.WongM.W.WentrupC., “Iminoethenone radical cation: Tandem mass spectrometry and ab initio MO studies”, J. Phys. Chem.98, 5801 (1994). doi: 10.1021/j100074a002
24.
van ThuijlJ.van HouteJ.J.MaquestiauA.FlammangR.De MeyerC., “The formation and structure of [C2H3N]•+ radical cations”, Org. Mass Spectrom.12, 196 (1977). doi: 10.1002/oms.1210120403
25.
CordermanR.R.LeBretonP.R.ButtrillS.E.WilliamsonA.D.BeauchampJ.L., “Photoionization and ion cyclotron resonance studies of the ion chemistry of ethylene oxide”, J. Chem. Phys.65, 4929 (1976). doi: 10.1063/1.432969
26.
van ThuijlJ.KlebeK.J.van HouteJ.J., “Fragmentation behaviour of 1-methylimidazole and 1-methylpyrazole upon electron impact”, Org. Mass Spectrom.7, 1165 (1973). doi: 10.1002/oms.1210071005
