Gas‐phase reactions of SiH_n⁺ (n = 1,2) with NF₃: A computational investigation on the detailed mechanistic aspects

Abstract

The mechanism of the gas-phase reactions of SiH(n)(+) (n = 1,2) with NF(3) were investigated by ab initio calculations at the MP2 and CAS-MCSCF level of theory. In the reaction of SiH(+), the kinetically relevant intermediates are the two isomeric forms of fluorine-coordinated intermediate HSi-F-NF(2)(+). These species arise from the exoergic attack of SiH(+) to one of the F atoms of NF(3) and undergo two competitive processes, namely an isomerization and subsequent dissociation into SiF(+) + HNF(2) , and a singlet-triplet crossing so to form the spin-forbidden products HSiF(+) + NF(2). The reaction of SiH(2)(+) with NF(3) involves instead the concomitant formation of the nitrogen-coordinated complex H(2)Si-NF(3)(+) and of the fluorine-coordinated complex H(2)Si-F-NF(2)(+). The latter isomer directly dissociates into NF(2)(+) + H(2)SiF, whereas the former species preferably undergoes the passage through a conical intersection point so to form a H(2) SiF-NF(2)(+) isomer, which eventually dissociates into H(2)SiF(+) and NF(2).

Experimental and Theoretical Study on the Gas-Phase Reactions of Germyl Radicals with NF3: Homolytic Substitution at the Nitrogen Atom vs Fluorine Abstraction

“…In this work, following our interest in the gas-phase reactions between the fluorinated compounds and hydrides of C, Si, and Ge, we decided to further investigate the S H 2 reactions at the nitrogen atom using NF 3 as a substrate. In particular, taking into account that the homolytic bimolecular substitution mechanism that occurs at the nitrogen atom by means of the germyl radical is still not explored, we studied the reactions between GeH 3 radicals generated by X-ray irradiation and NF 3 .…”