The xenon-difluoronitrenium cation F2N-Xe+, a novel xenon-nitrogen species, is obtained in the gas phase by the nucleophilic displacement of HF from protonated NF3 by Xe. MP2 and CCSD(T) theoretical calculations reveal that this process is exothermic and exoergic by ca. 3 kcal mol-1. The conceivable alternative formation of the inserted isomer FN-XeF+ is instead endothermic by as much as 40-60 kcal mol-1, and is not attainable under the employed ion trap mass spectrometric (ITMS) conditions. F2N-Xe+ is theoretically characterized as a weak electrostatic complex between NF2 + and Xe, with a Xe-N bond distance of 2.4-2.5 Å, and a dissociation enthalpy and free energy into its constituting fragments of 15 and 8 kcal mol-1, respectively. F2N-Xe+ is therefore more fragile than the xenon-nitrenium ions (FO2S)2NXe+, F5SN(H)Xe+, and F5TeN(H)Xe+ observed in the condensed phase as AsF6 - or Sb3F16 - salts [1-4]. It is however still stable enough to be observed in the gas phase. Other otherwise elusive xenon-nitrogen species could be obtained under these experimental conditions
Xenon-Nitrogen Chemistry: Gas-phase Generation by ITMS and Theoretical Investigation of the Xenon-Difluoronitrenium Ion F2N-Xe+
OPERTI, Lorenza;RABEZZANA, Roberto;TURCO, Francesca;
2011-01-01
Abstract
The xenon-difluoronitrenium cation F2N-Xe+, a novel xenon-nitrogen species, is obtained in the gas phase by the nucleophilic displacement of HF from protonated NF3 by Xe. MP2 and CCSD(T) theoretical calculations reveal that this process is exothermic and exoergic by ca. 3 kcal mol-1. The conceivable alternative formation of the inserted isomer FN-XeF+ is instead endothermic by as much as 40-60 kcal mol-1, and is not attainable under the employed ion trap mass spectrometric (ITMS) conditions. F2N-Xe+ is theoretically characterized as a weak electrostatic complex between NF2 + and Xe, with a Xe-N bond distance of 2.4-2.5 Å, and a dissociation enthalpy and free energy into its constituting fragments of 15 and 8 kcal mol-1, respectively. F2N-Xe+ is therefore more fragile than the xenon-nitrenium ions (FO2S)2NXe+, F5SN(H)Xe+, and F5TeN(H)Xe+ observed in the condensed phase as AsF6 - or Sb3F16 - salts [1-4]. It is however still stable enough to be observed in the gas phase. Other otherwise elusive xenon-nitrogen species could be obtained under these experimental conditions
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