Intact Four‐atom Organic Tetracation Stabilized by Charge Localization in the Gas Phase

Abstract

Several features distinguish intact multiply charged molecular cations (MMCs) from other species such as monocations and polycations: high potential energy, high electron affinity, a high density of electronic states with various spin multiplicities, and charge-dependent reactions. However, repulsive Coulombic interactions make MMCs quite unstable, and hence small organic MMCs are currently not readily available. Herein, we report that the isolated four-atom molecule diiodoacetylene survives after the removal of four electrons via tunneling. We show that the tetracation remains metastable towards dissociation because of the localization (91-95 %) of the positive charges on the terminal iodine atoms, ensuring minimum Coulomb repulsion between adjacent atoms as well as maximum charge-induced attractive dipole interactions between iodine and carbon. Our approach making use of iodines as the positively charged sites enables small organic MMCs to remain intact.

Multiple ionization and Coulomb explosion of molecules, molecular complexes, clusters and solid surfaces

“…The liberation of hydrogen atoms by tunneling as well as ejection of protons by Coulomb explosion is expected to take place easily in organic MMCs. In Figure 5 are shown organic molecular tetracations that have been produced by several methods such as EI [121,122], collision with high energy projectiles [123] and femtosecond laser ionization [42,55,124,125]. The organic molecular tetracation of ovalene (C32H14), a large polycyclic aromatic hydrocarbon that has a structure containing 10 fused benzene rings that enable delocalization of multiple charges, was detected for the first time using EI (80 eV) [121].…”

“…On the contrary, intact MMCs are definitively identified by the mass-to-charge ratio, isotope pattern, and narrower peak width than those of lower-charged ions by using TOF-MS. The lifetime of intact MMCs are longer than a few hundred ns, for example, diiodoacetylene tetracation does not decay completely at least for 11 μs, which is the flight time from the ion source to the entrance of the second mass analyzer (reflectron) in TOF-MS [55]. In contrast to Coulomb explosions of short-lived MMCs, the chemistry of intact MMCs have been only rarely explored (see Section 2.2).…”

Charge Transfer and Metastable Ion Dissociation of Multiply Charged Molecular Cations Observed by Using Reflectron Time‐of‐Flight Mass Spectrometry

“…In this article, we show that particular product ions emerged from multiply charged precursor ion are not detected under the condition for the analysis of the product ions of singly charged precursor ion. We use multiply charged molecular cations (MMCs), [10][11][12] which are prepared in abundance by sequential tunnel ionization in intense femtosecond laser fields, [13][14][15] to show the behavior of product ions that transmit the reflectron in refTOF-MS. Hexafluorobenzene (C 6 F 6 ), which has small mass and simple dissociation channels, is chosen as a model molecule to analyze charge transfer reactions and metastable ion dissociations of MMCs.…”

Selection of a Single Isotope of Multiply Charged Xenon (AXez+, A=128–136, z=1–6) by Using a Bradbury–Nielsen Ion Gate

“…For dications, lifetimes on the order of milliseconds to seconds were investigated by using ion storage ring technology . Recently, we reported that quadruply charged four‐atomic molecular cations were produced in abundance and were intact enough to be detected after 10 μs from their birth . Several attractive features, such as high electron affinity, high potential energy, high density of electronic states with various spin multiplicities, and charge‐dependent chemistry, are expected for such long‐lived MMCs .…”

“…[7,8] Recently,w er eported that quadruply chargedfour-atomic molecular cations were produced in abundance and were intact enough to be detected after 10 msf rom their birth. [9] Several attractive features, such as high electron affinity,h ighp otentiale nergy,h igh density of electronic states with variouss pinm ultiplicities,a nd charge-dependent chemistry,a re expected for such long-lived MMCs. [8,[10][11][12][13][14][15] However, little is knowna bout the physical and chemical properties of MMCs,a lthough their characteristic features are attractive as novel reactive speciesf rom both fundamentala nd applied scientific perspectives.…”