Gas-Phase Reactivity of (C5H5Mg)+Complexes:  An Experimental and Theoretical Study

Berthelot, Jacques; Luna, A.; Tortajada, Jeanine

doi:10.1021/jp981562w

Cited by 6 publications

(3 citation statements)

References 54 publications

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“…This is consistent with the formal description of ( c -C 5 H 5 )Mg + as ( c -C 5 H 5 ) - Mg 2+ . A very recent theoretical study of this cation indicates an interaction that is typical of an ionic bond and NBO analysis indicates a natural charge of 1.8 for Mg . Also, it is relevant to note from Figure that the measured onsets of multicollision-induced dissociation for ( c -C 5 H 5 )Mg + −RH are about 2 times higher than that for Mg + −RH, which also is consistent with electrostatic bonding with the alkane.…”

Section: Resultssupporting

confidence: 63%

Gas-Phase Coordination of Mg⁺, (c-C₅H₅)Mg⁺, and (c-C₅H₅)₂Mg⁺ with Saturated Hydrocarbons

et al. 2000

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The coordination of the electronic ground states of Mg+, (c-C5H5)Mg+, and (c-C5H5)2Mg+ with the straight-chain saturated hydrocarbons methane, ethane, n-propane, n-butane, n-pentane, n-hexane, and n-heptane has been investigated in the gas phase in helium at room temperature and moderate pressures. Reaction rate coefficients and product distributions were measured with the selected-ion flow tube (SIFT) technique operating at 294 ± 3 K and a helium buffer-gas pressure of 0.35 ± 0.01 Torr. Rate coefficients were measured for all observed ligation steps (or upper limits in the case of nonreactions), and bond connectivities in the coordinated ions were probed with multicollision-induced dissociation. Only single ligation was observed. The rate of ligation was found to depend on the size of the saturated hydrocarbon, increasing with increasing size until the collision rate is reached, and on the degree of ligation with c-C5H5. Mg+ was found to be unreactive with methane and ethane, k < 10-13 cm3 molecule-1 s-1, but ligation was observed with the other hydrocarbons, k ≥ 7 × 10-12 cm3 molecule-1 s-1. Single ligation of Mg+ with c-C5H5 substantially enhances the efficiency of subsequent ligation: the ligation is rapid, k ≥ 1.4 × 10-10 cm3 molecule-1 s-1, with all the saturated hydrocarbons investigated. Double ligation with c-C5H5 completely shuts down the efficiency of ligation: no reaction was observed between the saturated hydrocarbons and the full-sandwich magnesocene cation, k < 10-13 cm3 molecule-1 s-1. A linear correlation is reported between the measured thresholds for multicollision-induced dissociation and the polarizability of the hydrocarbon ligand. With a view to published calculations by Bauschlicher et al. for Mg+−CH4 and Mg+−C2H4, this correlation is consistent with end-on structures for the Mg+−L and (c-C5H5)Mg+−L species observed in this study. A detailed study using density functional theory for the interaction of Mg+ with three rotamers of n-pentane indicates that interconversion of different isomers of Mg+−n-C5H12 should be easy, even at room temperature and that the ligated species Mg+−n-C5H12 is “dynamic” rather than “static”. Stronger bonding (by a factor of about two) is indicated for (c-C5H5)Mg+−L by the multicollision CID experiments, and this is consistent with a formal description of (c-C5H5)Mg+ as (c-C5H5)-Mg2+.

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Section: Resultssupporting

confidence: 63%

Gas-Phase Coordination of Mg⁺, (c-C₅H₅)Mg⁺, and (c-C₅H₅)₂Mg⁺ with Saturated Hydrocarbons

et al. 2000

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“…Their higher stability was explained in terms of formal Cp-Mg 2+ complexes. No binding energies of these hydrocarbon complexes were provided, but an earlier theoretical study, 23 using the natural bond order (NBO) analysis, indeed reported a rather high positive charge of 1.6e on the ligated Mg.…”

Section: Resultsmentioning

confidence: 99%

MALDI-TOF-MS of Saturated Polyolefins by Coordination of Metal Cations: A Theoretical Study

et al. 2001

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Density functional calculations were applied to obtain binding energies for metal cation-oligomer complexes of n-alkanes and poly(ethylene glycol)s (PEG). The B3LYP/6-31G* energies for complexing metal cations (Na+, Li+, Co+, Cu+, Zn+, and Zn2+) with straight chain aliphatics (C n H2 n +2, n = 1−12) are in excellent agreement with the limited available experimental and theoretical data. The strength of the complexes increases with an increasing degree of polymerization and with a decreasing size of the metal ion. The weakest calculated complex is Na+−CH4 (7.8 kcal/mol) and the strongest is Co+−dodecane (52.0 kcal/mol). Smaller sized cations, such as Li+, induce more polarized hydrocarbons. Transition metals give stronger complexes than the main group metals because their d-electrons shield the nuclear charge less effectively. M+−methane binding energies, ranging from 12.6 to 23.1 kcal/mol, are also reported for Sc+, Y+, La+, Cu+, Ag+, and Au+. Doubly charged metal ions give much stronger complexes, that is, 67.1 kcal/mol for Zn2+−CH4. Methane binding energies of ca. 20 kcal/mol are obtained when the Be2+, Mg2+, Fe2+, and Zn2+ dications are ligated with a cyclopentadienyl anion. The poly(ethylene glycol)s (HO−[C2H4O] n −H, n = 1−5) bind significantly stronger to the metal cations (Na+ and Cu+) than the aliphatics. The Na+−monomer (C2H6O2) already has a complex strength of 48.5 kcal/mol, while that of the pentamer (C10H22O6), which is the smallest observable Na+−complex by MALDI-TOF-MS, amounts to 88 kcal/mol. The corresponding Cu+ complexes are even stronger with a value of 79.6 kcal/mol for Cu+−C2H6O2. Binding energies of 53.3 and 64.1 kcal/mol are calculated for the respective K+−tetramer and K+−pentamer of which the pentamer is also observed spectroscopically.

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“…In addition, the energy profile can contribute to better comprehension of the dissociation channels obtained by collisional activation and tandem mass spectrometry studies. − Research groups have been devoted to many works involving mass spectrometry in combination with computational chemistry. ,− Although the latter technique has been widely applied to gas-phase chemistry, topological analysis of the electron density by the atoms in molecules (AIM) method has been rarely used for elucidation of fragmentation mechanism. , Thus, application of parameters generated by AIM shall aid analysis of the results regarding the fragmentation mechanism.…”

Section: Introductionmentioning

confidence: 99%

Application of the Atoms in Molecules Theory and Computational Chemistry in Mass Spectrometry Analysis of 1,4-Naphthoquinone Derivatives

Vessecchi

Lopes

et al. 2011

J. Phys. Chem. A

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Mass spectrometry analysis of 2-(acylamino)-1,4-naphthoquinone derivatives was carried out using electrospray ionization ion source in combination with tandem mass spectrometry. Protonated molecules were dissociated by application of the collision-induced dissociation (CID), and the protonation sites were suggested on the basis of the HOMO, molecular electrostatic potential map (MEP), proton affinity, and Fukui functions calculated by B3LYP/6-31+G(d,p). The main fragmentation mechanisms undergone by the protonated ions were elucidated on the basis of energy, geometry, and topology analysis of equilibrium geometries. Compounds exhibiting only aliphatic hydrogens at the lateral chain undergo interesting ketene elimination. On the other hand, only the benzoylium ion formation is detected for 2-benzoylamino-1,4-naphthoquinone. The bonds geometric and atoms in molecules parameters give evidence that acidic hydrogen atoms play an important role in the fragmentation pathways.

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Gas-Phase Reactivity of (C₅H₅Mg)⁺Complexes: An Experimental and Theoretical Study

Cited by 6 publications

References 54 publications

Gas-Phase Coordination of Mg⁺, (c-C₅H₅)Mg⁺, and (c-C₅H₅)₂Mg⁺ with Saturated Hydrocarbons

Gas-Phase Coordination of Mg⁺, (c-C₅H₅)Mg⁺, and (c-C₅H₅)₂Mg⁺ with Saturated Hydrocarbons

MALDI-TOF-MS of Saturated Polyolefins by Coordination of Metal Cations: A Theoretical Study

Application of the Atoms in Molecules Theory and Computational Chemistry in Mass Spectrometry Analysis of 1,4-Naphthoquinone Derivatives

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Gas-Phase Reactivity of (C5H5Mg)+Complexes: An Experimental and Theoretical Study

Cited by 6 publications

References 54 publications

Gas-Phase Coordination of Mg+, (c-C5H5)Mg+, and (c-C5H5)2Mg+ with Saturated Hydrocarbons

Gas-Phase Coordination of Mg+, (c-C5H5)Mg+, and (c-C5H5)2Mg+ with Saturated Hydrocarbons

MALDI-TOF-MS of Saturated Polyolefins by Coordination of Metal Cations: A Theoretical Study

Application of the Atoms in Molecules Theory and Computational Chemistry in Mass Spectrometry Analysis of 1,4-Naphthoquinone Derivatives

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Product

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Gas-Phase Reactivity of (C₅H₅Mg)⁺Complexes: An Experimental and Theoretical Study

Gas-Phase Coordination of Mg⁺, (c-C₅H₅)Mg⁺, and (c-C₅H₅)₂Mg⁺ with Saturated Hydrocarbons

Gas-Phase Coordination of Mg⁺, (c-C₅H₅)Mg⁺, and (c-C₅H₅)₂Mg⁺ with Saturated Hydrocarbons