Gas-Phase transition-metal negative ion chemistry

Squires, Robert R.

doi:10.1021/cr00079a008

Cited by 119 publications

(40 citation statements)

References 49 publications

(77 reference statements)

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“…lo', Whereas the formal Cr"' compound CrO,CI+ as well as the lanthanide dioxide CeO: presumably lead to acetaldehyde. collisional activation studies of the [C,H,/ CH,ReO:] system and related ions revealed that for this rhenium-based organometal oxide, formation of oxirane is indeed observed and competes with olefin metathesis (Scheme 15) Interestingly, the competition of olefin epoxidation and metathesis parallels the chemistry of CH,ReO, in the condensed phase, where it was demonstrated that this organometal oxide catalyzes both reactions. …”

Section: Ethenementioning

confidence: 95%

CH and CC Bond Activation by Bare Transition‐Metal Oxide Cations in the Gas Phase

Schröder

Schwarz

1995

Angew. Chem. Int. Ed. Engl.

486

340

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Over the last decade the gas-phase chemistry of bare transition-metal oxide cations MO+ has received considerable attention. This interest is primarily due to the particular role of metal oxides in the oxidation of organic compounds in a variety of chemical and biochemical transformations. At a molecular level the simplest model system for these processes deals with reactions of bare metaloxide ions in the gas phase. Due to the high oxophilicities of the early transition metals. their monoxide cations MO' d o not mediate 0-atom transfer to any organic compounds at all. In contrast, monoxide cations of late transition metals can oxygenate a variety of hydrocarbons. and the most reactive ions. MnO', FeO', NiO', OsO'. and PtO+, even activate methane. Insight into the reaction mechanisms of these oxidation processes can be obtained by analysis of react ion kinetics, isotope effects, product distributions etc., and for the reactions of MO+ with alkanes the initial C-H bond activation by MO' is often rate-determining. Interestingly, the high reactivity of some MO' ions is not always associated with a decrease in regioselectivity; for example, FeO ions induce regiospecific 7 G -H bond activation of dialkylketones in the gas phase. The situation for the epoxidation of olefins in the gas phase turns out to be even more complex than for condensedphase analogues. This is primarily because the metal ion that mediates 0-atom transfer to the olefin also catalyzes the isomerization of the epoxides formed, to afford the energetically more stable aldehydes or ketones. Aromatic compounds can also be hydroxylated by MOf ions, and particularly the OXiddtion of benzene by bare FeO+ ions in the gas phase reveals striking parallels to the metabolism of arenes. Furthermore, the storing capabilities of ion cyclotron resonance mass spectrometers even permit the design of catalytic processes in which a single metal ion converts more than one substrate molecule into an oxygenated product in a sequence of strictly bimolecular reactions. The most outstanding examples are the Pt + -mediated oxidation of methane by molecular oxygen and the Co'-mediated hydroxylation of benzene by N,O as oxidant. Finally, the key features of the gas-phase reactions are compared with observations in condensed-phase systems in which metal oxides are anticipated as central intermediates. The result of this comparison is promising in the sense that, in general, the understanding of transition-metal-mediated oxidations in the gas phase may lead to a more uniform description of these processes at a molecular level. Ultimately. it is hoped that gas-phase studies will serve as one of the building blocks in the evolution of tailor-made catalysts.

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Section: Ethenementioning

confidence: 95%

CH and CC Bond Activation by Bare Transition‐Metal Oxide Cations in the Gas Phase

Schröder

Schwarz

1995

Angew. Chem. Int. Ed. Engl.

486

340

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“…1,2 However there are only a few studies concerning cobalt trifluoride. 3 Our investigations of cobalt di-and trifluoride fluorination by atomic fluorine 4 necessitate verification of cobalt trifluoride saturated vapor pressure.…”

Section: Mass Spectrometric Determination Of Cobalt Trifluoride Saturmentioning

confidence: 99%

“…In this section we would like to touch upon the nature of the processes responsible for CoF 2 All of these possibilities were considered. Cobalt tetrafluoride and molecular fluorine were not observed.…”

Section: Cobalt Difluoride Formationmentioning

confidence: 99%

Mass spectrometric determination of cobalt trifluoride saturated vapor pressure. Enthalpy of formation of gaseous CoF4 and CoF4−

Rau¹,

Chilingarov²,

Sidorov³

1997

Rapid Commun. Mass Spectrom.

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“…A mechanism consistent with reactions (l), (2), (4) and (5) is proposed' which involves insertion of the metal into the C-H bond of the aldehyde to give, after rearrangement, a final six-coordinate metal-hydrido intermediate…”

Section: Resultsmentioning

confidence: 85%

Gas‐phase chemistry of electron deficient organometallic anions: the reactions of [Cr(CO)₃]^{− ˙} and [Cr(CO)₄]^{− ˙} with aldehydes, ketones, esters and ethers

Gregor

1989

Org. Mass Spectrom.

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Gas-Phase transition-metal negative ion chemistry

Cited by 119 publications

References 49 publications

CH and CC Bond Activation by Bare Transition‐Metal Oxide Cations in the Gas Phase

CH and CC Bond Activation by Bare Transition‐Metal Oxide Cations in the Gas Phase

Mass spectrometric determination of cobalt trifluoride saturated vapor pressure. Enthalpy of formation of gaseous CoF4 and CoF4−

Gas‐phase chemistry of electron deficient organometallic anions: the reactions of [Cr(CO)₃]^{− ˙} and [Cr(CO)₄]^{− ˙} with aldehydes, ketones, esters and ethers

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Gas-Phase transition-metal negative ion chemistry

Cited by 119 publications

References 49 publications

CH and CC Bond Activation by Bare Transition‐Metal Oxide Cations in the Gas Phase

CH and CC Bond Activation by Bare Transition‐Metal Oxide Cations in the Gas Phase

Mass spectrometric determination of cobalt trifluoride saturated vapor pressure. Enthalpy of formation of gaseous CoF4 and CoF4−

Gas‐phase chemistry of electron deficient organometallic anions: the reactions of [Cr(CO)3]− ˙ and [Cr(CO)4]− ˙ with aldehydes, ketones, esters and ethers

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Gas‐phase chemistry of electron deficient organometallic anions: the reactions of [Cr(CO)₃]^{− ˙} and [Cr(CO)₄]^{− ˙} with aldehydes, ketones, esters and ethers