Electronic Structures and OH-Induced Atmospheric Degradation of CF3NSF2: A Potential Green Dielectric Replacement for SF6.
Electronic structures of [(trifluoromethyl)imino]sulfur difluoride (CF3NSF2) and degradation mechanisms by hydroxyl radical have been investigated using density functional theory (M06-2X), the complete basis set quadratic CBS-Q, and the explicitly correlated coupled-cluster methods [CCSD(T)-F12]. The d-function augmented correlation-consistent basis sets including triple- and quadruple-ξ were employed for the sulfur-containing species. It was found that CF3NSF2exists as two conformations connected by the internal rotation of CF3around the central NS bond. The distorted syn conformer is more stable than the symmetrical anti conformer. The nitrogen-sulfur link in CF3NSF2was revealed to be predominantly ionic CF3N--+SF2in structure rather than the conventional N═S double bond on the basis of natural bond orbital analysis. OH radical prefers to attach on the S atom of CF3NSF2along the opposite direction of the S-F bond via a nucleophilic addition mechanism with a barrier of 2.9 kcal/mol whereas the ON association pathway is negligible. Although many product channels are thermodynamically favorable, none of them is kinetically accessible because of the significant barriers along the reaction routes. However, the degradation of CF3NSF2by OH can be accelerated considerably in the presence of a single water molecule, which acts as a bridge for the consecutive proton migration within the floppy cyclic geometries. The half-life of CF3NSF2was estimated to be 2.5 year, and the final products are exclusively CF3NH and SF2O. Theoretical calculation supports that CF3NSF2is an environment-friendly green gas. It is worthy of testing its dielectric properties to replace SF6for practical use.
College of Electricaland Electronic Engineering, Hua Zhong University of Science and Technology , Wuhan 430074, People's Republic of China.|Wuhan NARI, State Grid Power Research Institute , Wuhan 430072, People's Republic of China.
Lin
L
Cheng
College of Chemistry and Molecular Sciences, Wuhan University , Wuhan 430072, People's Republic of China.
Xiaojuan
X
Yu
Wuhan NARI, State Grid Power Research Institute , Wuhan 430072, People's Republic of China.
Kun
K
Zhao
College of Chemistry and Molecular Sciences, Wuhan University , Wuhan 430072, People's Republic of China.
Hua
H
Hou
College of Chemistry and Molecular Sciences, Wuhan University , Wuhan 430072, People's Republic of China.
Baoshan
http://orcid.org/0000-0003-3417-9283
B
Wang