Polynitrogen compounds

This review, presented in three parts, summarizes the results concerning the molecular and electronic structure and the thermodynamic stability of polynitrogen compounds N n , with n ranging from 4 to 60, as revealed by quantum chemical calculations published in the past 30 years, and where available, by experimental observations. In the present Part 1, attention is paid to the tetranitrogen (N 4 ) and pentanitrogen (N 5 ) systems whose existence and stability have been demonstrated by recent experimental studies. The two following parts will be devoted to the properties of larger clusters, N n with n ≥6. The potential use of the nitrogen clusters as efficient, safe and environment-friendly high energy high-density materials (HEDM) will be discussed. The interactions between these polynitrogen compounds with metals, metal cations and metal complexes, and the factors influencing the ligand stability, will also be examined.