General trends in dissociations of medium-sized hydrocarbon dications

Milko, Petr; Schröder, Detlef; Schwarz, Helmut; Roithová, Jana

doi:10.1016/j.ijms.2008.05.027

Cited by 11 publications

(6 citation statements)

References 36 publications

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“…A possible rationale is that the ions most reactive toward methane have singlet ground states, possibly with a carbene-like site in analogy to the cycloheptatrienylidene structure of the C 7 H 6 2+ dication, which is the most stable dication of this composition and serves as a precursor for the C−C coupling with methane . This conjecture is further supported by similar odd−even electron alternations found in the unimolecular dissociation of hydrocarbon dications . However, in comparison with the corresponding pure hydrocarbon congeners, i.e., the corresponding medium-sized C m H n 2+ dications, it is important to point out that all of the C−C coupling reactions observed for the C m H n N 2+ dications bear rather low yields.…”

Section: Resultsmentioning

confidence: 57%

“…7b This conjecture is further supported by similar odd-even electron alternations found in the unimolecular dissociation of hydrocarbon dications. 22 However, in comparison with the corresponding pure hydrocarbon congeners, i.e., the corresponding medium-sized C m H n 2+ dications, 7 it is important to point out that all of the C-C coupling reactions observed for the C m H n N 2+ dications bear rather low yields. In fact, the relative intensity of the sum of the peaks corresponding to these reactions is systematically lower than 10%.…”

Section: Resultsmentioning

confidence: 99%

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Carbon−Carbon Coupling Reactions of Medium-Sized Nitrogen-Containing Dications

Zins

Schröder

2010

J. Phys. Chem. A

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The reactivity of molecular dications C(m)H(n)N(2+), generated by (dissociative) double ionization of different heteroaromatic compounds, with methane, ethane, and nitrogen is investigated using a triple-quadrupole mass spectrometer. About a quarter of the set of dications studied undergo carbon-carbon coupling reactions with methane, whereas only nonspecific reactions leading to the formation of monocations (such as proton-, electron- and hydride transfer as well as Coulomb explosions) occur in the presence of either ethane or nitrogen. Here, we report the reactivity observed for 42 different C(m)H(n)N(2+) dications formed via electron ionization of eleven different heteroaromatic precursors. The potential relevance of these results is discussed in the context of the growth of hydrocarbon species and their nitrogen-containing homologues at extremely low temperatures and pressures, such as in interstellar environments or the ionospheres of planets and moons, Saturn's moon Titan in particular.

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Section: Resultsmentioning

confidence: 57%

Section: Resultsmentioning

confidence: 99%

Carbon−Carbon Coupling Reactions of Medium-Sized Nitrogen-Containing Dications

Zins

Schröder

2010

J. Phys. Chem. A

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“…At first, the AE s determined above for the doubly charged dehydrogenation products lie only slightly above the second ionization energies of the neutral precursors, whereas sequential bond homolysis concomitant with expulsion of H atoms will require several electronvolts. Second, whereas losses of atomic hydrogen have indeed been observed for hydrocarbon dications C m H n 2+ , ,, their abundances follow an odd/even electron pattern. , Sequential H-atom losses are therefore unlikely to take place without detection of the intermediates C m H n −1 2+ , and the corresponding C 6 H n −1 N 2+ were not observed in our PI experiments with the nitrogen analogs. C 6 H n N 2 + → C 6 H n −2 N 2 + + H 2 C 6 H n N 2 + → C 5 H n −3 N + + CH 3 + C 6 H n …”

Section: Resultsmentioning

confidence: 57%

Growth Of Doubly Ionized C,H,N Compounds in the Presence of Methane

et al. 2009

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The molecular dications C(6)H(5)N(2+) generated via dissociative double ionization of 2- and 4-picoline, respectively, react with methane to form the C-C coupled products C(7)H(7)N(2+) concomitant with liberation of molecular hydrogen. Multipole-based mass spectrometric experiments and photoionization studies using synchrotron radiation demonstrate that this bond-forming reaction involves the corresponding dications in their electronic ground states. The reactions might hence be of relevance in the context of the growth of hydrocarbon species at extremely low temperatures and pressures, such as in the atmosphere of Titan. Whereas the parent [(CH(3))C(5)H(4)N](2+) dications of both picolines also show C-C coupling to a limited amount, the molecular dication of aniline, [C(6)H(5)NH(2)](2+), is almost unreactive toward methane.

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“…1 Comprehensive reviews on the physics and chemistry of these ions by Schröder and Schwarz, 2 by Mathur, 3 by Price, 4 by Milko et al, 5 and the papers appearing in the special issue of Ref. 1 present the reader with the important developments in this vibrant research area.…”

Section: Introductionmentioning

confidence: 99%

A theoretical study of SnF2+, SnCl2+, and SnO2+ and their experimental search

Batista

Lima

Franzreb

et al. 2012

The Journal of Chemical Physics

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We present a detailed theoretical study of the stability of the gas-phase diatomic dications SnF(2+), SnCl(2+), and SnO(2+) using ab initio computer calculations. The ground states of SnF(2+), SnCl(2+), and SnO(2+) are thermodynamically stable, respectively, with dissociation energies of 0.45, 0.30, and 0.42 eV. Whereas SnF(2+) dissociates into Sn(2+) + F, the long range behaviour of the potential energy curves of SnCl(2+) and SnO(2+) is repulsive and wide barrier heights due to avoided crossing act as a kind of effective dissociation energy. Their equilibrium internuclear distances are 4.855, 5.201, and 4.852 a(0), respectively. The double ionisation energies (T(e)) to form SnF(2+), SnCl(2+), and SnO(2+) from their respective neutral parents are 25.87, 23.71, and 25.97 eV. We combine our theoretical work with the experimental results of a search for these doubly positively charged diatomic molecules in the gas phase. SnO(2+) and SnF(2+) have been observed for prolonged oxygen ((16)O(-)) ion beam sputtering of a tin metal foil and of tin (II) fluoride (SnF(2)) powder, respectively, for ion flight times of about 10(-5) s through a magnetic-sector mass spectrometer. In addition, SnCl(2+) has been detected for (16)O(-) ion surface bombardment of stannous (tin (II)) chloride (SnCl(2)) powder. To our knowledge, SnF(2+) is a novel gas-phase molecule, whereas SnCl(2+) had been detected previously by electron-impact ionization mass spectrometry, and SnO(2+) had been observed before by spark source mass spectrometry as well as by atom probe mass spectrometry. We are not aware of any previous theoretical studies of these molecular systems.

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General trends in dissociations of medium-sized hydrocarbon dications

Cited by 11 publications

References 36 publications

Carbon−Carbon Coupling Reactions of Medium-Sized Nitrogen-Containing Dications

Carbon−Carbon Coupling Reactions of Medium-Sized Nitrogen-Containing Dications

Growth Of Doubly Ionized C,H,N Compounds in the Presence of Methane

A theoretical study of SnF2+, SnCl2+, and SnO2+ and their experimental search

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