Studies of the reactions of Group VIII transition-metal ions [iron(+), cobalt(+), and nickel(+)] with linear alkanes. Determination of reaction mechanisms and MCnH2n+ ion structures using Fourier transform mass spectrometry collision-induced dissociation

Jacobson, D. B.; Freiser, Ben S.

doi:10.1021/ja00354a003

Cited by 84 publications

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“…This branching ratio differs somewhat from 33/67 measured by GFA at energies <0.1 eV 6 and from 31/69 measured at thermal energies by Jacobson and Freiser using FTMS. 10 Better agreement is found with AB who report a branching ratio of 25/75 at ∼0.5 eV, 4 with van Koppen et al who found 23/77 at 0.05 eV, 9 and with Tonkyn et al who measure 24/76 at thermal energy in a flow tube. 11 The variability among these various measurements can be understood using the state-specific branching ratios measured by van Koppen et al at thermal energies.…”

Section: Resultssupporting

confidence: 78%

Probing the [CoC₃H₈]⁺Potential Energy Surface: A Detailed Guided-Ion Beam Study

1996

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The potential energy surface for the CoC 3 H 8 + system is examined in studies using a guided-ion beam tandem mass spectrometer in conjunction with a dc discharge/flow tube ion source. Bimolecular reactions of Co + + C 3 H 8 , Co + (C 3 H 6 ) + H 2 (D 2 ), Co + (C 2 H 4 ) + CH 4 (CD 4 ), and CoCH 2 + + C 2 H 6 are examined, as well as threshold collisional activation of Co + (C 3 H 8 ). The results allow details of the [CoC 3 H 8 ] + potential energy surface to be elucidated. A key feature of the potential energy surface is a rate limiting transition state for C-H bond activation processes, measured as 0.29 ( 0.10 eV below the Co + + C 3 H 8 asymptote. For C-C bond activation, experiments are interpreted to yield two rate-limiting transition states lying 0.08 ( 0.08 eV below and 0.05 ( 0.04 eV above this asymptote. From the threshold collision activation study, we determine a 0 K bond dissociation energy for D 0 (Co + -C 3 H 8 ) of 1.34 ( 0.06 eV. We also determine a lower limit for D 0 (Co + -C 2 H 5 ) of 1.76 ( 0.09 eV (estimated as 2.00 ( 0.11 eV), and D 0 (DCo + -C 2 H 4 ) ) 0.95 ( 0.18 eV. On the basis of recent theoretical studies, we assign the rate-limiting TSs to multicenter elimination structures and show that this reaction scheme can explain both the present and previous experimental observations.

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Section: Resultssupporting

confidence: 78%

Probing the [CoC₃H₈]⁺Potential Energy Surface: A Detailed Guided-Ion Beam Study

1996

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“…[48] This functional was combined with the standard D95** polarized, double-z basis set for carbon and hydrogen. For cobalt, the (14s9p5d) primitive set of Wachters [49] is supplemented with one diffuse p-function (a 0.1219) and one diffuse d-function according [38], [39] % 0.5 IB G 2 5 7 5 [40] < 0.2 IB G 1 9 8 1 [37] < 0.1 IB G 3 3 6 7 [21] 0.05 IB G 2 3 7 3 [41] TE [b] ICR 31 69 [20] TE FR 24 76 [42] TE TMS 4 96 [41] TE TMS [d] 18 82 [18] TE TMS [e] 53 47 [18] [a] CB crossed beams; IB G ion beam plus gas cell; ICR ion cyclotron resonance; FR flow reactor at 0. to Hay, [50,51] resulting in a (6211111 j 33121 j 411) 3 [8s5p3d] contraction. The transition states reported here were located by unconstrained geometry optimization using analytical gradients.…”

Section: Electronic Structure Calculationsmentioning

confidence: 99%

Crossed-Beam Study of Co+(3F4)+Propane: Experiment and Density Functional Theory

Reichert

Holthausen

et al. 2000

Chem. Eur. J.

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A pulsed beam of Co+(3F4) crosses a pulsed beam of C3H8 or C3D8 gas under single collision conditions at collision energies of 0.01 eV and 0.21 eV. After a variable time delay t(ext) = 1-8 micros a fast high voltage pulse extracts product ions into a field-free flight tube for mass analysis. Consistent with earlier work, we observe prompt CoC3H6+ +H2 elimination products in 3:1 excess over CoC2H4+ +CH4 products at 0.21 eV on a 2-10 micros time scale. Long-lived CoC3H8+ complexes fragment predominantly back to Co+ +C3H8 reactants and to H2 elimination products on a 6-24 micros time scale. Density functional theory (B3LYP) calculations provide energies, geometries, and harmonic vibrational frequencies at key stationary points for use in a statistical rate model of the reaction. By adjusting two key multicenter transition state (MCTS) energies downward by 4-7 kcal mol(-1), we obtain good agreement with our decay time results and with the cross section versus collision energy of Armentrout and co-workers from 0.1-1.0 eV. B3LYP theory succeeds in finding relative energies of the MCTSs leading to CH4 and H2 in the proper order to explain the different product branching ratio for Co+ (which favors H2 over CH4) compared with its nearest neighbors Fe+ and Ni+ (which favor CH4 over H2).

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“…It is thought that the CpCo ⅐ϩ ion preferentially attacks the C™H bond in the initial oxidative addition step due to the strong s character of metal-ligand antibonding orbital, i.e., LUMO (lowest unoccupied molecular orbital) [21]. It is interesting that the CpCo ⅐ϩ ion reacts with n-alkanes exclusively by dehydrogenation, while the Co ϩ ion reacts by dehydrogenation and dealkylation [15][16][17]31]. It has been demonstrated by deuterium labeling, collision-activated dissociation, and ion-molecule studies that the apparent dehydrogenation reaction between Co ϩ and n-butane goes by way of a C™C bond insertion [17,31].…”

Section: Single and Double Dehydrogenationmentioning

confidence: 99%

“…It is interesting that the CpCo ⅐ϩ ion reacts with n-alkanes exclusively by dehydrogenation, while the Co ϩ ion reacts by dehydrogenation and dealkylation [15][16][17]31]. It has been demonstrated by deuterium labeling, collision-activated dissociation, and ion-molecule studies that the apparent dehydrogenation reaction between Co ϩ and n-butane goes by way of a C™C bond insertion [17,31]. This result may explain, at least in part, the extensive fragmentation observed for the laser desorption MS analysis of the higher molecular mass alkane C-28 when Co ϩ was used as the cationization reagent [15].…”

Section: Single and Double Dehydrogenationmentioning

confidence: 99%

Molecular mass determination of saturated hydrocarbons: reactivity of η⁵-cyclopentadienylcobalt ion (CpCo^·+) and linear alkanes up to C-30

Byrd

Guttman

Ridge

2003

J. Am. Soc. Mass Spectrom.

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The present study demonstrates the feasibility of the 5 -cyclopentadienylcobalt ion (CpCo ⅐ϩ ) as a suitable cationization reagent for saturated hydrocarbon analysis by mass spectrometry. Ion/molecule reactions of CpCo ⅐ϩ and three medium chain-length n-alkanes were examined using Fourier-transform ion cyclotron resonance mass spectrometry. Second-order rate constants and reaction efficiencies were determined for the reactions studied. Loss of two hydrogen molecules from the CpCo-alkane ion complex was found to dominate all reactions (Ն80%). Furthermore, this dehydrogenation reaction efficiency increases with increasing chain length. These preliminary results suggest that the CpCo ⅐ϩ ion may be a promising cationization reagent of longer chain saturated hydrocarbons and polyolefins.

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Studies of the reactions of Group VIII transition-metal ions [iron(+), cobalt(+), and nickel(+)] with linear alkanes. Determination of reaction mechanisms and MCnH2n+ ion structures using Fourier transform mass spectrometry collision-induced dissociation

Cited by 84 publications

References 0 publications

Probing the [CoC₃H₈]⁺Potential Energy Surface: A Detailed Guided-Ion Beam Study

Probing the [CoC₃H₈]⁺Potential Energy Surface: A Detailed Guided-Ion Beam Study

Crossed-Beam Study of Co+(3F4)+Propane: Experiment and Density Functional Theory

Molecular mass determination of saturated hydrocarbons: reactivity of η⁵-cyclopentadienylcobalt ion (CpCo^·+) and linear alkanes up to C-30

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Studies of the reactions of Group VIII transition-metal ions [iron(+), cobalt(+), and nickel(+)] with linear alkanes. Determination of reaction mechanisms and MCnH2n+ ion structures using Fourier transform mass spectrometry collision-induced dissociation

Cited by 84 publications

References 0 publications

Probing the [CoC3H8]+Potential Energy Surface: A Detailed Guided-Ion Beam Study

Probing the [CoC3H8]+Potential Energy Surface: A Detailed Guided-Ion Beam Study

Crossed-Beam Study of Co+(3F4)+Propane: Experiment and Density Functional Theory

Molecular mass determination of saturated hydrocarbons: reactivity of η5-cyclopentadienylcobalt ion (CpCo·+) and linear alkanes up to C-30

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Probing the [CoC₃H₈]⁺Potential Energy Surface: A Detailed Guided-Ion Beam Study

Probing the [CoC₃H₈]⁺Potential Energy Surface: A Detailed Guided-Ion Beam Study

Molecular mass determination of saturated hydrocarbons: reactivity of η⁵-cyclopentadienylcobalt ion (CpCo^·+) and linear alkanes up to C-30