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

Paola Antoniotti; Paola Benzi; Domenica Marabello; Daniele Rosso

doi:10.1021/acsomega.9b03729

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

ACS Omega. 2020 Mar 3;5(10):4907-4914. doi: 10.1021/acsomega.9b03729. eCollection 2020 Mar 17.

Authors

Paola Antoniotti^{1

2}, Paola Benzi^{1

2}, Domenica Marabello^{1

2}, Daniele Rosso¹

Affiliations

¹ Dipartimento di Chimica, Università di Torino, Via P. Giuria, 7, 10125 Torino, Italy.
² CRISDI, Interdepartmental Centre for Crystallography, University of Turin, 10124 Torino, Italy.

Abstract

In this paper, we report on the unexplored reaction mechanisms of bimolecular homolytic substitution (S_H2) between GeH₃ radicals and the nitrogen atom of NF₃. The S_H2 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 GeH₄ and NF₃ show the formation of GeH₃-NF₂ and GeH₃-F. The trend of product yields as a function of the increase in GeH₄ partial pressure in the irradiated mixtures evidences the predominant role of GeH₃ radicals. Particularly, the S_H2 mechanism can be hypothesized for the reaction between GeH₃ radicals and NF₃ molecules leading to GeH₃-NF₂. This mechanism is further confirmed by the increase in GeH₃-NF₂ yield observed if O₂ 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 GeH₃-NF₂ product actually occurs from a bimolecular homolytic substitution by the GeH₃ radical, which attacks the N atom of NF₃, and this reaction is in competition with the fluorine abstraction reaction leading to GeH₃F, even if other mechanisms may be involved in the formation of this product.