Mass spectrometry of π‐complexes of transition metals 38—keto‐enol tautomerization of molecular ions of acetyl‐ and propionyl‐ferrocenes in the gas phase

Zagorevskii, D. V.; Volkova, Тatyana V.; Antipov, B. G.; Nekrasov, Yurii S.

doi:10.1002/oms.1210260907

Cited by 6 publications

(5 citation statements)

References 13 publications

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“…It is also possible to view the mechanism from an alternative perspective, that of an acid-catalyzed keto/enol tautomerization (although CH 3 CHO is not strictly a ketone). In this context, we note that there are several precedents for the occurrence of keto/enol tautomerization in ion/molecule chemistry. − However, these previous studies have reported the occurrence of fragmentation of metal ion adducts of ketones 64,65 or of base-catalyzed 66,67 isomerization of ionized acetone. There do not appear to be any previous studies of an acid-catalyzed keto/enol tautomerization, and for this reason, the reaction of CH 2 CHOH 2 + with PN (or with another appropriate molecule with a proton affinity between PA(CH 3 CH O ) and PA( C H 2 CHOH), such as those in Table ) may be of considerable interest as a fundamental example of a generic organic chemistry process…”

Section: Resultsmentioning

confidence: 89%

CH₂CHOH₂⁺ + PN: A Proton-Transfer Triple Play

Petrie

2005

J. Phys. Chem. A

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Quantum chemical calculations are used to explore the proton-transfer reactivity of O-protonated vinyl alcohol, CH2CHOH2+, with phosphorus nitride, PN. This reaction is relevant to the chemical evolution of interstellar clouds, since O-protonated vinyl alcohol has been postulated (and tentatively identified) as a product of the association reaction between interstellar H3O+ and C2H2, while PN is the most widespread and abundant phosphorus-containing molecule seen in astrophysical environments. Furthermore, the reaction exhibits an unusual mechanistic feature, namely, an extended "proton-transport catalysis" mechanism, which we characterize here as a "proton-transfer triple play". The reaction proceeds initially by proton transfer from CH2CHOH2+ to PN, then from PNH+ to CH2CHOH, and finally from CH3CHOH+ to PN, where the emphasized atom indicates the resultant site of protonation/deprotonation. Thus, the ultimate overall bimolecular proton-transfer reaction is expected to occur as CH2CHOH2+ + PN --> CH3CHO + PNH+; that is, the apparent favored product channel exhibits not only proton transfer but also keto/enol tautomerization. The triple-play mechanism can be rationalized in terms of the proton affinities of vinyl alcohol, acetaldehyde, and phosphorus nitride, which here are satisfactorily reproduced by high-level ab initio calculations. Other neutrals with a proton affinity appropriate for the possible triple-play mechanism converting CH2CHOH2+ to CH3CHO are also identified, with a view to encouraging experimental investigation of this mechanism.

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Section: Resultsmentioning

confidence: 89%

CH₂CHOH₂⁺ + PN: A Proton-Transfer Triple Play

Petrie

2005

J. Phys. Chem. A

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“…The dissociation of their molecular ions (R = Me, Et, CF 3 , Ph, etc.) produced a high yield of FcCO + . , No suitable precursors for neutral FcCO • were found, and so for this reason only NR experiments were performed in the attempt to generate and detect this radical.…”

Section: Resultsmentioning

confidence: 99%

“…The latter can be achieved via direct interaction between the carbonyl group of the acetyl or benzoyloxy substituent with the positively charged metal atom. Similar reactions, resulting in the migration of the anion (or radical) from the side chain of the substituent in the cyclopentadienyl ligand to the Fe atom, are common for the dissociation of substituted ferrocenes. ,,,19a The energy requirements for this electron transfer are determined by the difference in ionization energies of the corresponding molecular orbitals. For example, the difference between the ionization energy on the ligand π-system or an O-atom in 1,1‘-diacetylferrocene and that on the metal atom is ∼1.8 eV .…”

Section: Resultsmentioning

confidence: 99%

Generation and Identification of Neutral CpFeC₅H₄X (X = O, CH₂, CO) Complexes in the Gas Phase by Tandem Mass Spectrometry

Zagorevskii

Holmes

1997

Organometallics

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Tandem mass spectrometry experiments were performed to generate and identify neutral FcX (Fc = CpFeC5H4; X = O, CH2, CO) complexes having a formal 19-electron configuration. Neutralization−reionization mass spectra of FcX+ ions showed recovery signals corresponding to the formation of their neutral counterparts. FcO• and FcCH2 • were also identified by means of the collision-induced (dissociative) ionization method as neutral products of the unimolecular fragmentation of molecular ions of the monosubstituted ferrocenes. Appearance energies of FcX ions and neutrals were measured. Activation energies for the [FcX−R]•+ bond cleavage were significantly higher than those in similar aromatic systems, PhXR•+. It was proposed that only a part of this energy was related to the FcX−R bond dissociation, the remainder being required for the intramolecular electron transfer from the ligand to the metal atom. The Fc+−CO bond dissociation energy in [FcCO]+ ions was substantially lower than that in the benzoyl ion. The weakness of the (neutral) Fc−CO bond was considered to be the major reason for the poor survival of FcCO• radicals in the neutralization−reionization of FcCO+ ions.

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“…The nido-cluster structure of type I ions is responsible for the formation of some ions in the MI mass spectrum of the acetyl derivative (Ic). This is exemplified by H 20 elimination, which according to previous work [10], results from keto-enol isomerization in the acyl group.…”

Section: Carbonyl Derivatives Mnc Sh4cor +mentioning

confidence: 85%

Metastable ion study of substituted cyclopentadienylmanganese cations in the gas phase

Zagorevskii

Nekrasov

Holmes

1993

J. Am. Soc. Mass Spectrom.

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The behavior of some substituted cyclopentadienylmanganese ions has been studied by tandem mass spectrometry. This metastable ion study showed that only C5H5Mn(+) and (C5H4CN)Mn(+) ions retain their nido-cluster structure (1), which is characterized by a simple metal-ligand bond cleavage. Other substituted ions, RXC5H4Mn(+), rearrange to a different extent, depending on the nature of the substituent. The first rearrangement step is R radical migration to the central metal atom, leading to RMnC5H4X(+)-type ions (2). These ions decompose by elimination of X (for X=CO) or with formation of RMnX(+), but further rearrangements can also occur. These are the reverse migration of R from the metal atom to the π-ligand (for R=H, Ph) and cyclopentadienyl ring expansion (for X=CH2). Collisional activation mass spectra contained an Mn(+) ion peak, which can indicate the existence of stable type 1 structures for most cyclopentadienylmanganese ions. Carboxyl and hydroxymethyl derivatives exist, presumably as ions of type 2. The neutralization-reionization mass spectra of RXC5H4Mn(+) ions are also discussed.

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Mass spectrometry of π‐complexes of transition metals 38—keto‐enol tautomerization of molecular ions of acetyl‐ and propionyl‐ferrocenes in the gas phase

Cited by 6 publications

References 13 publications

CH₂CHOH₂⁺ + PN: A Proton-Transfer Triple Play

CH₂CHOH₂⁺ + PN: A Proton-Transfer Triple Play

Generation and Identification of Neutral CpFeC₅H₄X (X = O, CH₂, CO) Complexes in the Gas Phase by Tandem Mass Spectrometry

Metastable ion study of substituted cyclopentadienylmanganese cations in the gas phase

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Mass spectrometry of π‐complexes of transition metals 38—keto‐enol tautomerization of molecular ions of acetyl‐ and propionyl‐ferrocenes in the gas phase

Cited by 6 publications

References 13 publications

CH2CHOH2+ + PN: A Proton-Transfer Triple Play

CH2CHOH2+ + PN: A Proton-Transfer Triple Play

Generation and Identification of Neutral CpFeC5H4X (X = O, CH2, CO) Complexes in the Gas Phase by Tandem Mass Spectrometry

Metastable ion study of substituted cyclopentadienylmanganese cations in the gas phase

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CH₂CHOH₂⁺ + PN: A Proton-Transfer Triple Play

CH₂CHOH₂⁺ + PN: A Proton-Transfer Triple Play

Generation and Identification of Neutral CpFeC₅H₄X (X = O, CH₂, CO) Complexes in the Gas Phase by Tandem Mass Spectrometry