Selective Preparation of Phosphorus Mononitride (P≡N) from Phosphinoazide and Reversible Oxidation to Phosphinonitrene

Abstract

The interstellar candidate phosphorus mononitride PN, a metastable species, was generated through high-vacuum flash pyrolysis of (ophenyldioxyl)phosphinoazide in cryogenic matrices. Although the PN stretching band was not directly detected because of its low infrared intensity and possible overlaps with other strong bands, o-benzoquinone, carbon monoxide, and cyclopentadienone as additional fragmentation products were clearly identified. Moreover, an elusive o-benzoquinone-PN complex formed when (o-phenyldioxyl)phosphinoazide was exposed to UV irradiation at λ = 254 nm. Its recombination to (o-phenyldioxyl)-λ 5 -phosphinonitrile was observed upon irradiation with the light at λ = 523 nm, which demonstrates for the first time the reactivity of PN towards an organic molecule. Energy profile computations at the B3LYP/def2-TZVP density functional theory level reveal a concerted mechanism. To provide further evidence, UV/Vis spectra of the precursor and the irradiation products were recorded and agree well with time-dependent DFT computations.

Spectroscopic Identification and Photochemistry of Astrochemically Relevant Phosphorus-bearing Molecules [O, C, N, P] and [2O, C, N, P]

“…Similar to the decomposition of cyclic OC(N 2 ) (→ CO + N 2 ), the cyclic phosphorus analog favors exothermic fragmentation to PN and CO. Recently, the photoreaction between PN and benzoquinone has been observed in Ar matrix at 10 K, and the activation barrier for this exothermic process is about 27 kcal mol −1 (Qian et al 2023). In contrast, the reverse reaction between PN and CO to the formation of PNCO is endothermic with a higher barrier (TS4).…”

“…Chemically, phosphorus mononitride (PN) is much more reactive than the nitrogen congener N 2 and it polymerizes very rapidly at ambient conditions. Recently, the synthesis and reactions of PN have been extensively explored (Kinjo et al 2010;Eckhardt et al 2022;Qian et al 2023). By analogy, PO is a transient heavy analog of nitrogen monoxide (NO), and its reactivity as a free species remains barely explored (Sterenberg et al 2002).…”

Preparation and Photochemistry of Parent Triplet Vinylarsinidene

“…Vinylphosphinidene ( 2 ) and vinylarsinidene ( 3 ) are equally unreported higher congeners of 1 (Scheme B). It has been proposed that 2 is produced as a fleeting intermediate in the pyrolysis of vinylphosphirane, which is subsequently converted to phosphapropyne. − Phosphirane- − and diazide-based compounds − and phosphines are viable photochemical/thermal sources for the synthesis of highly reactive (organic)phosphorus species. Recently, we exemplified that phenylarsenic diazide can be used to prepare triplet phenylarsinidene under matrix isolation conditions .…”