C4F7N with excellent insulation performance has been proposed to replace the traditional SF6 as a new insulating medium in power equipment. In the present study, the molecular structure and radiative efficiency (RE) of C4F7N are calculated and compared with SF6 based on DFT calculation. The decomposition of pure C4F7N and the basic interactions between C4F7N and hydroxyl radical in the constructed co-crystal of C4F7N-H2O have been simulated by applying Monte-Carlo calculation and Car-Parrinello molecular dynamics (CPMD) method, in order to obtain reasonable and full-scale atmospheric dissociation processes. Then the detailed decomposition pathways are learned with DFT method of M062X. The rate constants of different pathways are further applied for calculating the atmosphere lifetime of C4F7N, to evaluate the possibility of applying it as an alternative gas of SF6 in power equipment. All the atmospheric chemical behaviours are determined by electronic structure and reflected by the decomposition pathways of C4F7N with interacting with hydroxyl radicals. Rather than traditional hypothesizing reaction models, this study provides a reasonable and practicable method to evaluate more alternative protective gas for understand the greenhouse effect.

This work reports a theoretical study of a novel family of multi-coordinated noble gas (Ng) complexes, Xe(AuF)n (n = 2-4). Geometrical optimization at the LC-ωPBE-D3/def2TZVPP level locates two types of structures based on the bond-bending isomerism induced by an intramolecular competition between Xe-Au covalent bonding and Au···Au aurophilic interactions. They both comprise a center Xe atom serving as an electron donor binding to AuF moieties, but pronouncedly differ in the Au-Au distance and Au-Xe-Au bending angle. Comprehensive chemical bonding analysis undisputedly demonstrates that aurophilic interactions exist and affect the strength of Xe-Au bonds whose covalent nature is evident. By scanning the potential energy surface of Xe(AuF)2 with arbitrary one atom being substituted by its analogue, we found only Xe(AuF)2 and Xe(AuCl)2 feature bond-bending isomerism, due to the highly electronegative F/Cl atom inducing strongly covalent Xe-Au bond via electron donation-feedback mechanism. The present work predicts multi-coordinated Ng-metal complexes and demonstrates the bond-bending isomerism, which could be an interesting addition and call out more attentions to the research field of Ng chemistry.

Due to it is potential application in the field of high energy density materials, how to stabilize cyclopentazolate anion (cyclo-N5-) has attracted many interests theoretically and experimentally. Therefore, a series of ion salts containing [cyclo-N5]- were synthesized and studied. The instability of [cyclo-N5]- is caused by the five lone pairs of electrons localized on five neighbored N atoms. In this work, we expect if the [cyclo-N5]- can be stabilized by the coordination with acidic ligands, by weakening the multi repulsion from the lone pairs to stabilize the [cyclo-N5]-. The two compounds of [N5(BH3)5]-, and [N5(AgCN)5]- have been designed and compared based on the Lewis acid-base theory. [N5(H2O)5]- is designed to evaluate the effect of hydrogen bond in the stabilization. For all the structures, we study the bonding properties and thermal stabilities based on the analysis of electronic structures and Car-Parrinello molecular dynamics (CPMD) simulations. The results indicate it is a effective method to stabilize [cyclo-N5]- by introducing the Lewis acid. Our insights on [cyclo-N5]- compounds with high thermal stability under ambient conditions will provide a new idea for the research and synthesis of new high energetic [cyclo-N5]- series compounds.