| 1. |
- Ceppatelli, Matteo, et al.
(författare)
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High-Pressure and High-Temperature Chemistry of Phosphorus and Nitrogen: Synthesis and Characterization of α- and γ-P3N5
- 2022
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 61:31, s. 12165-12180
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Tidskriftsartikel (refereegranskat)abstract
- The direct chemical reactivity between phosphorus and nitrogen was induced under high-pressure and high-temperature conditions (9.1 GPa and 2000-2500 K), generated by a laser-heated diamond anvil cell and studied by synchrotron X-ray diffraction, Raman spectroscopy, and DFT calculations. alpha-P3N5 and gamma-P3N5 were identified as reaction products. The structural parameters and vibrational frequencies of gamma-P3N5 were characterized as a function of pressure during room-temperature compression and decompression to ambient conditions, determining the equation of state of the material up to 32.6 GPa and providing insight about the lattice dynamics of the unit cell during compression, which essentially proceeds through the rotation of the PN5 square pyramids and the distortion of the PN4 tetrahedra. Although the identification of alpha-P3N5 demonstrates for the first time the direct synthesis of this compound from the elements, its detection in the outer regions of the laser-heated area suggests alpha-P3N5 as an intermediate step in the progressive nitridation of phosphorus toward the formation of gamma-P3N5 with increasing coordination number of P by N from 4 to 5. No evidence of a higher-pressure phase transition was observed, excluding the existence of predicted structures containing octahedrally hexacoordinated P atoms in the investigated pressure range.
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| 2. |
- Marcos, Rocio, et al.
(författare)
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Mechanistic Studies on NaHCO3 Hydrogenation and HCOOH Dehydrogenation Reactions Catalysed by a Fe-II Linear Tetraphosphine Complex
- 2018
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Ingår i: Chemistry - A European Journal. - : John Wiley & Sons. - 0947-6539 .- 1521-3765. ; 24:20, s. 5366-5372
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Tidskriftsartikel (refereegranskat)abstract
- We present a theoretical extension of the previously published bicarbonate hydrogenation to formate and formic acid dehydrogenation catalysed by Fe-II complexes bearing the linear tetraphosphine ligand tetraphos-1. The hydrogenation reaction was found to proceed at the singlet surface with two competing pathways: A)H-2 association to the Fe-H species followed by deprotonation to give a Fe(H)(2) intermediate, which then reacts with CO2 to give formate. B)CO2 insertion into the Fe-H bond, followed by H-2 association and subsequent deprotonation. B was found to be slightly preferred with an activation energy of 22.8kcalmol(-1), compared to 25.3 for A. Further we have reassigned the Fe-H complex, as a Fe(H)(H-2), which undergoes extremely rapid hydrogen exchange.
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