In the past dibenzo-7λ -phosphanorbornadiene derivatives have already served as suitable precursors for the release of small phosphorus bearing molecules with only anthracene as a leaving group and byproduct. According to the literature chlorophosphine ClPA was synthesized and stirred with an excess of sodium azide (NaN3, 5 equiv.) in tetrahydrofuran (THF) at -20 °C. The addition of lithium chloride (LiCl, 2 equiv.) as a phase-transfer catalyst to solubilize azide ions through conversion of insoluble NaN3 into soluble LiN3 and NaCl proved to be highly efficient in reducing the reaction time to 7-10 days and a crude yield of azidophosphine N3PA as a colorless solid of up to 70% after workup (Scheme 2, Figure ). Single crystals of N3PA grown from diethyl ether at -20 °C were characterized in a single crystal X-ray diffraction experiment and the molecular structure is depicted in Figure (see also Table ). The structure is in line with a strong infrared band for the azide functional group at 2042 cm -1 (Figure ) and a single signal in the proton decoupled 31 P{ 1 H} NMR spectrum at δ 180.6 ppm (Figure ) that is split into a triplet in the proton coupled P NMR spectrum with a coupling constant to the two bridgehead protons of anthracene of 2 JPH = 14.5 Hz. Isotopically 15 N labeled N3PA, was synthesized from sodium azide-1-15 N following the same procedure. We obtained a statistical mixture with the 15 N isotope bonded to phosphorus as well as at the terminal end of the azide unit. Due to 31 P- N coupling the signal in the 31 P{ 1 H} NMR is split into a doublet that overlaps with the singlet for the terminal N labeled N3PA (Figure ). The singlet is not exactly in the center of the doublet because of the isotopic shift. We observed two singlet signals at δ 310 and δ 197 ppm in the N NMR for both isotopologues that, however, did not split into doublets (Figure ). ); P1-C8, 1.8882(15); N1-N2, 1.2341 (18); and N2-N3, 1.1325 (19). Selected interatomic bond angles (°): C1-P1-C8, 80.15 (7); P1-N1-N2, 115.22 (11). B: Explosive decomposition of N3PA followed by molecular beam mass spectrometry (MBMS).