Stabilization of the [cyclo‐N₅]⁻ anion by Lewis acid‐base interactions

Abstract

It is an attractive problem to stabilize cyclopentazolate anion [cyclo‐N5]− due to its promising application in the field of high‐energy density materials. The instability of [cyclo‐N5]− is caused by the repulsion of the neighbored lone pairs of electrons localized on N atoms. In this study, two anions of [N5(BH3)5]− and [N5(AgCN)5]− have been designed to reduce the intramolecular repulsion. [N5(H2O)5]− is designed to evaluate the effect of intramolecular hydrogen bond on the stabilization. For all the structures, we apply density functional theory and the Car‐Parrinello molecular dynamics method to study the bonding properties and thermal stabilities. Based on the results, we confirm that the individual [cyclo‐N5]− anion can be effectively stabilized through coordination with acidic ligands rather than the hydrogen bond, which will provide a new method to synthesize full‐nitrogen compounds.