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Polyhedral nitrogen containing molecules such as prismatic P₃N₃- a hitherto elusive isovalent species of prismane (C₆H₆) - have attracted particular attention from the theoretical, physical, and synthetic chemistry communities. Here we report on the preparation of prismatic P₃N₃[1,2,3-triaza-4,5,6-triphosphatetracyclo[2.2.0.0^2,6.0^3,5]hexane] by exposing phosphine (PH₃) and nitrogen (N₂) ice mixtures to energetic electrons. Prismatic P₃N₃was detected in the gas phase and discriminated from its isomers utilizing isomer selective, tunable soft photoionization reflectron time-of-flight mass spectrometry during sublimation of the ices along with an isomer-selective photochemical processing converting prismatic P₃N₃to 1,2,4-triaza-3,5,6-triphosphabicyclo[2.2.0]hexa-2,5-diene (P₃N₃). In prismatic P₃N₃, the P–P, P–N, and N–N bonds are lengthened compared to those in, e.g., diphosphine (P₂H₄), di-anthracene stabilized phosphorus mononitride (PN), and hydrazine (N₂H₄), by typically 0.03–0.10 Å.  These findings advance our fundamental understanding of the chemical bonding of poly-nitrogen and poly-phosphorus systems and reveal a versatile pathway to produce exotic, ring-strained cage molecules.

Ices of acetylene (C₂H₂) and ammonia (NH₃) were irradiated with energetic electrons to simulate interstellar ices processed by galactic cosmic rays in order to investigate the formation of C₂H₃N isomers. Supported by quantum chemical calculations, experiments detected product molecules as they sublime from the ices using photoionization reflectron time‐of‐flight mass spectrometry (PI‐ReTOF‐MS). Isotopically‐labeled ices confirmed the C₂H₃N assignments while photon energies of 8.81 eV, 9.80 eV, and 10.49 eV were utilized to discriminate isomers based on their known ionization energies. Results indicate the formation of ethynamine (HCCNH₂) and 2H‐azirine (c‐H₂CCHN) in the irradiated C₂H₂:NH₃ices, and the energetics of their formation mechanisms are discussed. These findings suggest that these two isomers can form in interstellar ices and, upon sublimation during the hot core phase, could be detected using radio astronomy.

The identification of silicon‐substituted, complex organics carrying multiple functional groups by classical infrared spectroscopy is challenging because the group frequencies of functional groups often overlap. Photoionization (PI) reflectron time‐of‐fight mass spectrometry (ReTOF‐MS) in combination with temperature‐programmed desorption (TPD) holds certain advantages because molecules are identified after sublimation from the matrix into in the gas phase based on distinct ionization energies and sublimation temperatures. In this study, we reveal the detection of 1‐silaglycolaldehyde (HSiOCH₂OH), 2‐sila‐acetic acid (H₃SiCOOH), and 1,2‐disila‐acetaldehyde (H₃SiSiHO)—the silicon analogues of the well‐known glycolaldehyde (HCOCH₂OH), acetic acid (H₃CCOOH), and acetaldehyde (H₃CCHO), in the gas phase after preparation in silane (SiH₄)–carbon dioxide ices exposed to energetic electrons and subliming the neutral reaction products formed within the ices into the gas phase.