Nitrogen backbone oligomers

TL;DR

This study demonstrates the formation of nitrogen backbone oligomers through high-pressure reactions of nitrogen and hydrogen, revealing potential pathways for synthesizing high-energy nitrogen-based materials.

Contribution

It reports the first experimental and theoretical evidence of nitrogen backbone oligomers formed at high pressures and temperatures, with insights into their stability and transformation.

Findings

Nitrogen and hydrogen react at ~35 GPa to form nitrogen backbone oligomers.

Oligomers transform into hydrazine below 10 GPa upon pressure release.

Formation of nitrogen-hydrogen compounds is energetically favorable above 2 GPa.

Abstract

In contrast to carbon, which forms long polymeric chains, all-nitrogen chains are very unstable. Here we found that nitrogen and hydrogen directly react at room temperature and pressures of about 35 GPa forming a mixture of nitrogen backbone oligomers - chains of single-bonded nitrogen atom with the rest of the bonds terminated with hydrogen atoms - as identified by IR absorption, Raman, X-ray diffraction experiments and theoretical calculations. The pressure required for the synthesis strongly decreases with temperature to about 20 GPa at 550 K. At releasing pressures below about 10 GPa, the product transforms into hydrazine. Our findings might open a way for the practical synthesis of these extremely high energetic materials as the formation of nitrogen-hydrogen compounds is favorable already at pressures above 2 GPa according to the calculations.