Benzenium ions of varying deuterium content have been formed by H+/D+ transfer and exchange processes with neutral benzene in the gas phase at 10-8−103 Torr. Brønsted acid reactivity with benzene itself is characterized by comparable efficiencies in the wide pressure range examined and by significant primary kinetic isotope effects in the competitive H+ vs D+ transfer. The reactivity of benzenium ions with selected bases is highly dependent on structural features of the ensuing collision complex. When the benzenium−benzene complex is allowed to reach thermal equilibrium with the environment at the upper pressure limit allowed by the radiolytic technique, a rate constant of 109 s-1 is obtained at 40 °C for an elementary D+ transfer step within the complex. An estimated rate of ca. 107 s-1 at 40 °C is derived for the D+ shift within the aromatic ring from a temperature dependence radiolytic study. Accordingly, complete H/D scrambling in C6(H,D)7+ ions is observed in the long-lived (10-3−1 s) ions sampled by FA-SIFT or FT-ICR mass spectrometry and is verified only at the highest temperature, 120 °C, of radiolytic experiments. All gathered evidence points to a σ-complex structure for protonated benzene.

Bronsted acid behavior of C6(H,D)7+ benzenium ions. A combined approach by radiolytic, FA-SIFT and FT-ICR methodologies / Chiavarino, Barbara; Crestoni, Maria Elisa; Fornarini, Simonetta; Depuy, C. H.; Gareyev, R.. - In: THE JOURNAL OF PHYSICAL CHEMISTRY. - ISSN 0022-3654. - STAMPA. - 100(1996), pp. 16201-16208. [10.1021/jp961322l]

Bronsted acid behavior of C6(H,D)7+ benzenium ions. A combined approach by radiolytic, FA-SIFT and FT-ICR methodologies

CHIAVARINO, Barbara;CRESTONI, Maria Elisa;FORNARINI, Simonetta;
1996

Abstract

Benzenium ions of varying deuterium content have been formed by H+/D+ transfer and exchange processes with neutral benzene in the gas phase at 10-8−103 Torr. Brønsted acid reactivity with benzene itself is characterized by comparable efficiencies in the wide pressure range examined and by significant primary kinetic isotope effects in the competitive H+ vs D+ transfer. The reactivity of benzenium ions with selected bases is highly dependent on structural features of the ensuing collision complex. When the benzenium−benzene complex is allowed to reach thermal equilibrium with the environment at the upper pressure limit allowed by the radiolytic technique, a rate constant of 109 s-1 is obtained at 40 °C for an elementary D+ transfer step within the complex. An estimated rate of ca. 107 s-1 at 40 °C is derived for the D+ shift within the aromatic ring from a temperature dependence radiolytic study. Accordingly, complete H/D scrambling in C6(H,D)7+ ions is observed in the long-lived (10-3−1 s) ions sampled by FA-SIFT or FT-ICR mass spectrometry and is verified only at the highest temperature, 120 °C, of radiolytic experiments. All gathered evidence points to a σ-complex structure for protonated benzene.
File allegati a questo prodotto
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/79192
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 28
  • ???jsp.display-item.citation.isi??? 29
social impact