Thermal Stability and Stereoelectronic Effects on Trifluoromethyl Peroxynitrates: A Combined Experimental and Computational Approach.

Abstract

Organic peroxynitrates are important reservoir species in the atmosphere. In this work we examine the correlation between the structural features (geometric parameters and normal vibrational modes) of CF₃OONO₂, CF₃C(O)OONO₂, CF₃OC(O)OONO₂, and their thermal stabilities. The dissociation energy for the O─N bond, involving in the rupture of molecules was calculated using the Gaussian16 program, with the B3LYP/6–311 + G(2df) method and basis set (103.2, 118.2, and 115.8 kJ/mol for CF₃OONO₂, CF₃C(O)OONO₂, and CF₃OC(O)OONO₂, respectively) and compared with previously reported. The investigation of stereoelectronic effects on the O─N bond, such as anomeric and mesomeric interactions was performed to provide their influence in the dissociation energy values using a detailed NBO (Natural Bond Orbital) analysis. Results indicate that the anomeric effect contributes significantly to the increase in electronic density on the antibonding O─N orbital (0.39553, 0.38689, and 0.38477 for CF₃OONO₂, CF₃OC(O)OONO₂, CF₃C(O)OONO₂ respectively). This is in agreement with the upward trend of the experimental and calculated dissociation energy (CF₃OONO₂ < CF₃OC(O)OONO₂ < CF₃C(O)OONO₂) and suggests that anomeric effect plays a key role in the bond dissociation.