Bond-forming reactions of molecular dications with rare gas atoms: Production of ArC2+ in the reaction CO2++Ar

Abstract

Integral cross sections for the bond-forming reaction CO 2ϩ ϩAr→ArC 2ϩ ϩO have been measured as a function of collision energy in a guided-ion beam mass spectrometer. The energy dependence is consistent with an endoergic reaction. Since the title reaction is in competition with several charge-transfer processes, the cross section at the maximum is only 0.023 Å 2 at a collision energy of about 3 eV. Simple kinematics considerations suggest that the falloff of the cross section at higher energies might be due to the vibrational predissociation of ArC 2ϩ. State correlation diagrams are used for discussing the reaction mechanism.

The formation of NO+ from the reaction of N22+ with O2

“…80,[82][83][84][85][86][87][88] As described above, the majority of the observed bondforming reactions of dications involve the formation of a pair of monocationic products. However, recently an alternative form of dicationic bond-forming reactivity has been detected involving the formation of doubly charged products: 69,86,[89][90][91][92] …”

“…[51][52][53][54]65,[67][68][69][70][71][72][73] Electron transfer, both dissociative and nondissociative, usually dominates the product ion yield in such encounters. When the electron is transferred from the neutral to the dication, a pair of monocations is formed.…”

Siliciumverbindungen von Neon und Argon

“…[8] Kürzlich ist es uns gelungen, mithilfe dieser Strategie die Organoargonverbindungen ArCH 2 + und ArC 2 H 2+ zu erzeugen, doch waren die Ausbeuten enttäu-schend niedrig; [9,10] geringe Mengen des diatomaren Dikations ArC 2+ wurden bereits vorher in stoßinduzierten Reaktionen von neutralem CO mit Ar 2+ und von neutralem Ar mit CO 2+ nachgewiesen. [11,12] Ein effizienteres dikationisches Reagens zur Aktivierung von Edelgasen muss nicht nur ein potentes Elektrophil sein, sondern darüber hinaus folgende Eigenschaften aufweisen: 1) Es sollte über eine Abgangsgruppe verfügen, die durch ein Edelgasatom ersetzt werden kann, ohne dass dabei eine beträchtliche kinetische Hinderung erfolgt (z. B. ein homolytischer Bindungsbruch).…”

Silicon Compounds of Neon and Argon

“…[9,10] Similarly, small amounts of the diatomic dication ArC 2+ had been observed in collisionally driven reactions of neutral CO with Ar 2+ and of neutral argon with CO 2+ . [11,12] A more efficient dicationic reagent for the attack of noble gases must not only be a potent superelectrophile, but it also needs to meet the following requirements: 1) It should possess a potential leaving group that can be replaced by a noble gas atom without a significant kinetic barrier being involved, such as a homolytic bond cleavage; 2) the preferred oxidation states of noble gases [13] mean that increased stabilities can be expected for even-electron compounds; for homolytic cleavage, the dicationic reagent should be a radical; 3) to prevent electron transfer processes during homolysis of the bond to the leaving group, which would afford an open-shell noble gas compound, the leaving group should have a high ionization energy (IE); and 4) the superelectrophilic dication should be accessible in quantities that suffice for reactivity studies in the gas phase. [14,15] The SiF 3 2+ dication is a promising candidate that may fulfill these requirements: it can be readily generated by dissociative double ionization of SiF 4 as a stable, neutral precursor, [16] it has a very high recombination energy RE-(SiF 3 2+ ) of about 22.4 eV, [17] which allows it to be classified as a superelectrophile, it has one surprisingly weak Si À F bond, with D(F 2 Si 2+ ÀF) = 1.97 eV, and the IE of fluorine as the potential leaving group is exceptionally large (17.4 eV).…”