Angewandte Chemie International Edition
© WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Cover Picture (Angew. Chem. Int. Ed. 13/14/1999)
The cover picture shows N5+, the first stable new homoleptic polynitrogen species in over 100 years. N5+ was prepared as its AsF6− salt in high yield by the reaction of N2F+AsF6− with HN3 at −78°C in anhydrous HF solution. It is a white solid that is marginally stable at room temperature and slowly decomposes with N2 evolution. The N5+ cation was characterized by low-temperature Raman, IR, and 14N and 15N NMR spectroscopy of the natural-abundance and 15N-labeled ions. in conjunction with extensive ab initio calculations. It has a planar V-shaped structure of C2v. symmetry. The new N5+ species is a powerful oxidizer and a potential high energy density propellant or explosive, with a calculated ΔH0f value of 1478 kJ mol−1 for the free gaseous cation. More on N5+ is reported by K. O. Christe et al. on pages 2004 ff.