title: Gas-phase reactions of XH3(+) (X = C, Si, Ge) with NF3: a comparative investigation on the detailed mechanistic aspects.
abstract: The gas-phase reaction of CH(3)(+) with NF(3) was investigated by ion trap mass spectrometry (ITMS). The observed products include NF(2)(+) and CH(2)F(+). Under the same experimental conditions, SiH(3)(+) reacts with NF(3) and forms up to six ionic products, namely (in order of decreasing efficiency) NF(2)(+), SiH(2)F(+), SiHF(2)(+), SiF(+), SiHF(+), and NHF(+). The GeH(3)(+) cation is instead totally unreactive toward NF(3). The different reactivity of XH(3)(+) (X = C, Si, Ge) toward NF(3) has been rationalized by ab initio calculations performed at the MP2 and coupled cluster level of theory. In the reaction of both CH(3)(+) and SiH(3)(+), the kinetically relevant intermediate is the fluorine-coordinated isomer H(3)X-F-NF(2)(+) (X = C, Si). This species forms from the exoergic attack of XH(3)(+) to one of the F atoms of NF(3) and undergoes dissociation and isomerization processes which eventually result in the experimentally observed products. The nitrogen-coordinated isomers H(3)X-NF(3)(+) (X = C, Si) were located as minimum-energy structures but do not play an active role in the reaction mechanism. The inertness of GeH(3)(+) toward NF(3) is also explained by the endoergic character of the dissociation processes involving the H(3)Ge-F-NF(2)(+) isomer.
authors.affiliation: Dipartimento di Chimica Generale e Chimica Organica and NIS Interdipartimental Centre of Excellence, Università degli Studi di Torino, C.so M. d' Azeglio, 48, 10125 Torino, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Antoniotti
authors.forename: Lorenza
authors.initials: L
authors.lastname: Operti
authors.forename: Roberto
authors.initials: R
authors.lastname: Rabezzana
authors.forename: Francesca
authors.initials: F
authors.lastname: Turco
authors.forename: Cristina
authors.initials: C
authors.lastname: Zanzottera
authors.forename: Maria
authors.initials: M
authors.lastname: Giordani
authors.forename: Felice
authors.initials: F
authors.lastname: Grandinetti