Taming Phosphorus Mononitride (PN)

Abstract

Phosphorus mononitride (PN) only has a fleeting existence on Earth and molecular precursors for a mild release of the molecule to enable chemical synthesis in solution do not exist. Here we report the synthesis of an anthracene (A) based molecular precursor (N3PA) that dissociates into dinitrogen (N2), A and PN in solution with a first order half-life of roughly t 1/2 = 30 min at room temperature associated with an activation enthalpy of ΔH ⧧ = 19.5 ± 1.7 kcal mol –1 and an activation entropy of ΔS ⧧ = −8.8 ± 0.8 cal mol –1 K –1 . Heated under vacuum N3PA decomposes in an explosive fashion at around 42 °C as demonstrated in a molecular beam mass spectrometry (MBMS) study. N3PA serves as a PN transfer reagent as demonstrated in the synthesis of [(dppe)Fe(Cp*)(NP)][BArF24]. Surprisingly, the terminal N-bonded linkage isomer is energetically preferred due to significant covalent iron pnictogen bond character and associated less unfavorable Pauli repulsion in the metal-ligand interaction.

Formation of the elusive tetrahedral P 3 N molecule

“…To sum up, the identification of the tetrahedral molecule 1,2,3triphospha-4-azatricyclo [1.1.0.0 2,4 ] butane (P 3 N, 10) progresses our fundamental understanding of the chemical bonding of highly strained binary pnictogen molecules carrying nitrogen and phosphorus and affords a formidable strategy to prepare traditionally "nonexisting" interpnictides such as PN 3 and P 2 N 2 via nonequilibrium chemistry, which have escaped any preparation and spectroscopic detection thus far. A "radical" approach to a "P 3 transfer chemistry" (26) or the controlled combination of diphosphorus (P 2 ) (37,38), diphosphatriazolate anion (P 2 N 3 − ) (39,40), and phosphorus mononitride (PN) (41,42) in solution might enable a preparative synthesis and isolation of molecular P 3 N (10) in the future.…”