The new harmonic inversion noise reduction method was applied to N-15 natural-abundance NMR spectroscopy and N5SbF6. This method is superior to conventional Fourier transform methods for processing FIN and permits the detection of natural abundance N-15 NMR signals with significantly reduced numbers of scans and improved sensitivity. In addition to the confirmation of the previously reported chemical shifts for N-5(+), the one bond coupling between N-beta and N-gamma could be observed for the first time. Its absolute value is compared to known coupling constants of other covalent azides and the free azide ion.