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

Abstract

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.

Doubly-charged ions in the planetary ionospheres: a review

“…The potential relevance of these results was discussed in the context of the growth of hydrocarbon species and their nitrogen-containing homologues, in particular in the ionospheric conditions observed in Saturn's moon Titan. [45][46][47][48]199,200 In conclusion, the experimental results on the few reactions of molecular doubly-charged ions which have been experimentally studied so far show that it is very difficult at the present stage to predict the ion products of such reactions. More laboratory work is therefore essential for all reactions which can occur in planetary upper atmospheres.…”

“…Hence activation of methane, to release bigger dication after carbon-carbon coupling reactions, has been demonstrated for aromatic species. [45][46][47][48] This mechanism will be further described in Section 4.1 describing the exotic chemistry of molecular dications. 57 This method, based on examination of data for a wide range of molecules, leads to calculation of double ionisation energies from the molecule single ionisation energies and maximum molecular dimensions.…”

Bond-forming and electron-transfer reactivity between Ar2+ and N2

“…14 This significant dicationic reactivity suggests that dication chemistry can play a role in ionospheric processes; 15 for example, dications are proposed to be involved in the chemistry of complex molecule assembly through carbon chain-growth. 14,[16][17][18][19] Atomic dications have been detected in planetary ionospheres. 20 However, it is difficult to unambiguously detect many ionospheric molecular dications using simple mass spectrometry, the usual sampling technique.…”

Bond-forming and electron-transfer reactivity between Ar2+ and O2

“…13 For example, dication reactions could be involved in the chemistry of complex molecule assembly. 12 Indeed, carbon-carbon coupling reactions have been observed following interactions of aromatic dications with methane, 14,15 ethyne 16 and benzene. 17 Despite their potential significance in ionospheric chemistry, the potential influence of dications on a variety of energized media is often neglected, due in part to the difficulty of unambiguous detection of dications by simple mass spectrometry.…”