Gas-phase reactions of XH3+ (X = C, Si, Ge) with NF3: a comparative investigation on the detailed mechanistic aspects

✍ Scribed by Paola Antoniotti; Lorenza Operti; Roberto Rabezzana; Francesca Turco; Cristina Zanzottera; Maria Giordani; Felice Grandinetti

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 507 KB
• Volume: 44
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/jms.1617

✦ Synopsis

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. Copyright © 2009 John Wiley & Sons, Ltd.