Xtreme Labs News
Abstract:Reacting praseodymium(IV) oxide with oxygen at 27 GPa in a diamond anvil cell yielded the oxide peroxide Pr2IV(O2)O3, which was characterized by single crystal X-ray diffraction on multi-grain samples, Raman spectroscopy and quantum theoretical calculations at various pressure points. The presence of tetravalent praseodymium ions is supported by electronic structure calculations, showing a band gap of ca. 1.2 eV, which is consistent with the anticipated chemical model of an ionic solid. Pr2(O2)O3 thus far represents the most oxygen rich phase of any binary compound of a lanthanoid and oxygen and is the first example of a peroxide anion next to Pr4+. Additionally, these results demonstrate that instead of oxidizing the praseodymium ions past their +IV oxidation state, oxygen undergoes a comproportionation to form peroxide anions. Direct oxidation of the oxide anions by Pr4+-ions was ruled out by a control experiment in argon instead of oxygen, where no oxidation of oxide ions was observed.
https://onlinelibrary.wiley.com/doi/full/10.1002/anie.202422929
20.08.2024 11:43
New paper on dysprosium carbides
Abstract:
Exploring the chemistry of materials at high pressure leads to discoveries of previously unknown compounds and phenomena. Here chemical reactions between elemental dysprosium and carbon were studied in laser-heated diamond anvil cells at pressures up to 95 GPa and temperatures of ∼2800 K. In situ single-crystal synchrotron X-ray diffraction (SCXRD) analysis of the reaction products revealed the formation of novel dysprosium carbides, γ-DyC2, Dy5C9, and γ-Dy4C5, along with previously reported Dy3C2 and Dy4C3. The crystal structures of γ-DyC2 and Dy5C9 feature infinite flat carbon polyacene-like ribbons and cis-polyacetylene-type chains, respectively. In the structure of γ-Dy4C5, carbon atoms form dimers and non-linear trimers. Dy3C2 contains ethanide-type carbon dumbbells, and Dy4C3 is methanide featuring single carbon atoms. Density functional theory calculations reproduce well the crystal structures of high-pressure dysprosium carbides and reveal conjugated π-electron systems in novel infinite carbon polyanions. This work demonstrates that complex carbon homoatomic species previously unknown in organic chemistry can be synthesized at high pressures by direct reactions of carbon with metals.
https://doi.org/10.1016/j.carbon.2024.119374
Exploring the chemistry of materials at high pressure leads to discoveries of previously unknown compounds and phenomena. Here chemical reactions between elemental dysprosium and carbon were studied in laser-heated diamond anvil cells at pressures up to 95 GPa and temperatures of ∼2800 K. In situ single-crystal synchrotron X-ray diffraction (SCXRD) analysis of the reaction products revealed the formation of novel dysprosium carbides, γ-DyC2, Dy5C9, and γ-Dy4C5, along with previously reported Dy3C2 and Dy4C3. The crystal structures of γ-DyC2 and Dy5C9 feature infinite flat carbon polyacene-like ribbons and cis-polyacetylene-type chains, respectively. In the structure of γ-Dy4C5, carbon atoms form dimers and non-linear trimers. Dy3C2 contains ethanide-type carbon dumbbells, and Dy4C3 is methanide featuring single carbon atoms. Density functional theory calculations reproduce well the crystal structures of high-pressure dysprosium carbides and reveal conjugated π-electron systems in novel infinite carbon polyanions. This work demonstrates that complex carbon homoatomic species previously unknown in organic chemistry can be synthesized at high pressures by direct reactions of carbon with metals.
https://doi.org/10.1016/j.carbon.2024.119374
