All manipulations were performed in a Vacuum Atmospheres model MO-40M glovebox under an inert atmosphere of purified N2. All solvents were obtained anhydrous and oxygen-free by bubble degassing (N2) and purification through columns of alumina and Q5, and storage over molecular sieves. Literature procedures were followed for the preparation of MgA•3THF, Me2NPA, ClPA 23 (A = C14H10, anthracene) and (dppe)Fe(Cp*)(Cl). Dimethylaminophosphorus dichloride (Me2NPCl2) was purchased from Alfa Aesar and used as received. Lithium chloride (LiCl) and sodium azide (NaN3) were purchased from Sigma Aldrich and used as received. Deuterated solvents were purchased from Cambridge Isotope Laboratories, degassed, and stored over molecular sieves for at least 48 h prior to use. Activated Charcoal Norit CA1 (Aldrich) and Celite 435 (EM Science) were dried by heating above 200 °C under dynamic vacuum for at least 48 h. All glassware was oven dried for at least 3 h at temperatures greater than 150 °C. NMR spectra were obtained on Bruker Avance 400, 401 or Bruker Neo 500 instruments equipped with Magnex Scientific superconducting magnets. H and C NMR spectra were referenced to residual protiated solvent resonances; P NMR spectra were referenced externally to 85% aqueous H3PO4 (δ = 0 ppm). Elemental analyses were performed by Midwest Microlab (Indianapolis, IN). High resolution mass spectral (HRMS) data were collected using a Jeol AccuTOF 4G LC-Plus mass spectrometer equipped with an Ion-Sense DART source. Data were calibrated to a sample of PEG-600 and were collected in positive ion mode. Samples were prepared in THF (ca. 10 μM concentration) and were briefly exposed to air (<5 s) before being placed in front of the DART source. Zero-field 57 Fe Mößbauer spectra were measured with a constant acceleration spectrometer at 80 K with isomer shifts reported relative to Fe foil at 298 K (0 mm s -1 ); data were analyzed and simulated with WMOSS v4. Synthesis of N3PA. Inside the glovebox, a 20 mL vial was charged with solid, colorless ClPA (500 mg, 2.04 mmol, 1.0 equiv.), NaN3 (675 mg, 10.38 mmol, 5.0 equiv.), LiCl (180 mg, 4.25 mmol, 2.0 equiv.) and a magnetic stir bar. Precooled (-20 °C) THF (15 mL) was added to the vial that was tightly closed with a cap and subsequently transported to the freezer inside the glovebox where it was stirred in the dark for 7 d at -20 °C. After seven days, all volatiles were removed under reduced pressure to yield a cream-colored solid residue. The solids were slurried in diethyl ether (4 x 20 mL) at room temperature and filtered through a celite:charcoal (1:1, 4 cm) plug in a 15 mL medium frit. The colorless ethereal solution was collected in a filter flask that was precooled in the liquid N2 immersed coldwell of the glovebox. Removal of solvent in vacuo from the colorless filtrate left a colorless solid that was weighed and stored in the freezer. Yields varied depending on how much anthracene was produced during the course of the reaction and the workup, giving up to 360 mg (70%) crude product with some anthracene impurities that rapidly decomposes at room temperature yielding a yellowish mixture of anthracene and PN polymers. The identity of the product was confirmed by NMR and IR spectroscopy as well as by an X-ray diffraction study performed on a crystal grown from diethyl ether at -20 °C (Figure ). A melting point for this material could not be determined. At 46.0 ± 0.5 °C the compound decomposes in an explosive fashion. DART HRMS(Q-TOF) m/z: [M + H] + Calcd for C14H11N3P 252.0685; Found 252.0698. H NMR (benzene-d6, 400 MHz, 25 °C) δ 7.41 (m, 2H), 7.33 (m, 2H), 7.17(m, 2H), 6.98 (m, 2H), 4.06 (d, 2H, 2 JPH = 12.6 Hz, H4) ppm. C{ 1 H} NMR (benzene-d6, 126 MHz, 25 °C) δ 145.9 (d, J = 3.1 Hz), 141.7 (d, J = 22.5 Hz), 126.5, 125.2, 124.5, 123.7 (d, J = 3.5 Hz), 56.8 (d, J = 18.9 Hz) ppm. P{ 1 H} NMR (benzene-d6, 162 MHz, 25 °C) δ 181 ppm. X-15 N 31 P{ 1 H} NMR (benzene-d6, 162 MHz, 25 °C) δ 181 (d, JPN = 77.9 Hz), 181 (s, b) ppm. N NMR (benzene-d6, 50.7 MHz, 25 °C) δ 310, 197 ppm.