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A team of scientists have synthesised a series of radical anions containing a rare four-atom nitrogen chain. 

Nitrogen is generally reluctant to form extended chains, largely because the N鈮�N triple bond is significantly stronger than N鈥揘 single or double bonds. As a result, radical anions based on four鈥慳tom nitrogen chains have been especially difficult to isolate, typically requiring extreme environments such as those found high in the Earth鈥檚 atmosphere. 

In findings, published in , researchers from the Universities of Manchester and Oxford have now demonstrated that a series of compounds containing {N鈧剗鈥⑩�� units can be reliably synthesised and characterised. The team prepared five distinct molecules, which showed surprising stability under ambient conditions, with one remaining intact in the solid state for several weeks. 

Further reactivity studies revealed that these chains can fragment into N鈧� and N鈧� species, and can also serve as a source of nitrene radical anions. 

Detailed analysis showed how the nitrogen chain can break into smaller fragments, specifically single鈥慳tom (N鈧�) and three鈥慳tom (N鈧�) units. The researchers also found that these chains can act as a source of highly reactive nitrene radical anions. 

These findings provide new insight into the fundamental chemistry of nitrogen and demonstrate ways to control its reactivity under realistic conditions. 

Nitrogen chains are considered high鈥慹nergy鈥慸ensity materials because they can release significant energy when they decompose into nitrogen gas. This property has long made them attractive for applications such as propellants, explosives, and gas鈥慻enerating systems. 

The ability to isolate and stabilise such molecules under ambient conditions could allow scientists to explore their use as 鈥渟torable鈥� reagents for transferring nitrogen groups in chemical reactions 

Beyond applications, the research offers a rare glimpse into a type of chemistry that plays a role in extreme environments, including the upper atmosphere where nitrogen chain ions have been detected. 

By recreating and stabilising these species in the laboratory, scientists can now investigate their properties in far greater detail, providing insights relevant to fields ranging from atmospheric chemistry to planetary science. 

This research was co-led by with Professor Meera Mehra, the University of Oxford, in collaboration with The University of Manchester鈥檚 , George F. S. Whitehead, , and, and Oxford鈥檚 Bono van IJzendoorn. First author was Oxford鈥檚 Reece Lister-Roberts.