Preparation of a neutral nitrogen allotrope hexanitrogen C_2h-N₆

Area of Science:

• Materials Science
• Inorganic Chemistry
• Energy Storage

Background:

• Polynitrogens (nitrogen allotropes) are promising clean energy-storage materials due to high energy content and harmless decomposition products.
• Extreme instability of polynitrogens presents significant synthetic challenges, with no neutral molecular nitrogen allotrope beyond N2 isolated previously.

Purpose of the Study:

• To synthesize and characterize a novel molecular nitrogen allotrope beyond N2.
• To explore the potential of new nitrogen allotropes for clean energy-storage applications.

Main Methods:

• Gas-phase reaction of chlorine or bromine with silver azide at room temperature.
• Trapping of the product in argon matrices at 10 K.
• Preparation of neat N6 film at 77 K.
• Characterization using infrared and UV-Vis spectroscopy, 15N-isotope labeling, and ab initio computations.

Main Results:

• Successful room-temperature preparation of molecular hexanitrogen (N6).
• Demonstrated stability of N6 through matrix isolation and film preparation at low temperatures.
• Spectroscopic and computational data confirm the structure and properties of N6.

Conclusions:

• The synthesis of a metastable molecular nitrogen allotrope (N6) expands fundamental knowledge of nitrogen chemistry.
• This breakthrough may pave the way for developing next-generation clean energy-storage technologies.