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Gas‐phase electrophilic fluorination of methanol by XeF + . Formation and characterization of protonated methyl hypofluorite and hypoxenite
Author(s) -
Attinà Marina,
Cacace Fulvio,
Cartoni Antonella,
Rosi Marzio
Publication year - 2001
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.140
Subject(s) - chemistry , proton affinity , protonation , xenon , xenon difluoride , electrophile , dissociation (chemistry) , adduct , methanol , bond dissociation energy , reactivity (psychology) , proton , fluorine , chemical ionization , reagent , ion , ionization , computational chemistry , inorganic chemistry , organic chemistry , medicine , physics , alternative medicine , pathology , quantum mechanics , catalysis
Abstract The reactivity of XeF + ions towards methanol was investigated in the gas phase by a combination of mass spectrometric techniques and theoretical methods. The charged reagent, generated from the chemical ionization of xenon difluoride, undergoes both fluorine and xenon transfer to methanol, following dissociation of primary (CH 3 OH)XeF + electrostatic adducts. Structural analysis performed by low‐energy collisionally activated dissociation and reactivity probing techniques, and the results of calculations carried out up to the B3LYP/CCSD(T) level of theory, concur in suggesting the formation of two different primary adducts of O—Xe—F and O—F—Xe connectivity that evolve into CH 3 O(H)Xe + and CH 3 O(H)F + , upon loss of F and Xe, respectively. Evidence was obtained for the structure of the fluorinated species, identified as O ‐protonated methyl hypofluorite. This finding allowed the first experimental evaluation of the proton affinity of CH 3 OF, which falls in the range 648.0–680.5 kJ mol −1 , not inconsistent with the 644.8 kJ mol −1 value calculated at the CCSD(T) level and 298 K. The proton affinity of methyl hypoxenite, CH 3 OXe, was theoretically calculated to amount to 747.7 kJ mol −1 . Copyright © 2001 John Wiley & Sons, Ltd.