High pressure and high temperature chemistry of the lowest Z pnictogens: Phosphorus and Nitrogen

High pressure and high temperature chemistry of the lowest Z pnictogens: Phosphorus and Nitrogen Matteo Ceppatellia,b,*, Demetrio Sceltaa,b, Manuel Serrano-Ruiza, Gaston Garbarinoc, Maurizio Peruzzinia, Roberto Binia,b,c a ICCOM-CNR, Institute of Chemistry of OrganoMetallic Compounds, National Research Council of Italy, Via Madonna del Piano 10, I-50019 Sesto Fiorentino, Firenze (Italy) b LENS, European Laboratory for Non-linear Spectroscopy, Via N. Carrara 1, I-50019 Sesto, Fiorentino, Firenze (Italy) c ESRF, European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000 Grenoble (France) d Dipartimento di Chimica "Ugo Schiff" dell'Universit/ degli Studi di Firenze, Via della Lastruccia 3, I-50019 Sesto Fiorentino, Firenze (Italy) * corresponding author: matteo.ceppatelli@iccom.cnr.it and ceppa@lens.unifi.it The recent synthesis of Phosphorene [1,2] by exfoliation of black Phosphorus (bP, A17) has raised the attention of the scientific community about the layered structures of this element. Within this perspective, pressure has been shown to be a very effective tool, because it provides experimental access to rhombohedral A7, another layered structure of P made by the stacking of blue Phosphorene, and has recently allowed to gain fundamental insight about the mechanism ruling the formation of chemical bonds between P layers, unveiling the existence of an intermediate p-sc structure between the layered A7 and the non-layered simple-cubic phases, and significantly raising the pressure limit where the layers of P can be observed up to ~30 GPa [3]. In this study we report the high pressure and high temperature chemistry of Phosphorus in the presence of N2 by means of state-of-the-art synchrotron XRD (ESRF-ID27), FTIR and Raman spectroscopy, using DAC for the generation of static high pressure and laser heating for in situ generation of high temperature. Besides the N-functionalization of Phosphorene, this study is relevant to the substantially unexplored chemistry of the lowest Z pnictogens and to the synthesis of new PN compounds. bP was laser heated under different pressure and temperature conditions, corresponding to different structures of Phosphorus (A17, A7 and sc), above and below the melting line of N2. The results indicate a pressure dependent chemical reactivity, leading to different reaction products, according to the applied pressure. The low pressure data demonstrate the first synthesis of ?-P3N5 from the elements, avoiding any precursor or byproduct [4]. Raman spectra and XRD patterns were acquired at high and ambient pressure, tracing the EOS of the material, and providing new experimental input about the existence of the predicted ?-P3N5 phase [5-6]. Thanks are expressed to EC through the European Research Council (ERC) for funding the project PHOSFUN "Phosphorene functionalization: a new platform for advanced multifunctional materials" (Grant Agreement No. 670173) through an ERC Advanced Grant. [1] H. Liu et al. ACS Nano 2014, 8, 4033-4041. [2] L. Li Nat. Nanotechnol. 2014, 9, 372-377. [3] D. Scelta et al. Angew. Chem. Int. Ed. 2017, 56, 14135-14140. [4] K. Landskron et al. Angew. Chem. Int. Ed. 2001, 40, 2643-2645. [5] J. Dong et al. Physica Status Solidi B, 2004, 210, 2319-2325. [6] P. Kroll et al. Chem. Eur. J. 2002, 8, 3530-3537.