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 paper, we report on the unexplored reaction mechanisms of bimolecular homolytic substitution (S H 2) between GeH 3 radicals and the nitrogen atom of NF 3 . The S H 2 reactions are studied both experimentally and theoretically with ab initio and density functional theory (DFT) calculations. The experimental results of X-ray irradiation of mixtures of GeH 4 and NF 3 show the formation of GeH 3 -NF 2 and GeH 3 -F. The trend of product yields as a function of the increase in GeH 4 partial pressure in the irradiated mixtures evidences the predominant role of GeH 3 radicals. Particularly, the S H 2 mechanism can be hypothesized for the reaction between GeH 3 radicals and NF 3 molecules leading to GeH 3 -NF 2 . This mechanism is further confirmed by the increase in GeH 3 -NF 2 yield observed if O 2 is added, as a radical scavenger, to the reaction mixture. In agreement with the experimental data, from the calculations performed at the CCSD(T) and G3B3 levels of theory, we observe that the GeH 3 -NF 2 product actually occurs from a bimolecular homolytic substitution by the GeH 3 radical, which attacks the N atom of NF 3 , and this reaction is in competition with the fluorine abstraction reaction leading to GeH 3 F, even if other mechanisms may be involved in the formation of this product.