Covalent Stabilization of the Iridium-Containing Oxyhydrides Sr2Mn0.5Ir0.5O3.25H0.75 and Sr2Mn0.5Ir0.5O2.66H1.33
Year: 2024
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide Reaction between Sr 2 Mn 0.5 Ir 0.5 O 4 and CaH 2 or LiH yields the iridium-containing oxyhydride phases Sr 2 Mn 0.5 Ir 0.5 O 3.25 H 0.75 or Sr 2 Mn 0.5 Ir 0.5 O 2.66 H 1.33, respectively. Analysis of Mn K-edge XANES data indicate the presence of Ir 3+ centers in these oxyhydride phases, whose low-spin d 6 configuration is consistent with the “covalent stabilization” of the metastable oxyhydride phases, as seen previously in analogous ruthenium and rhodium containing materials. Neutron powder diffraction data indicate the hydride ions are located exclusively within the “equatorial” anion sites of Sr 2 Mn 0.5 Ir 0.5 O 3.25 H 0.75 . In contrast, hydride ions are observed on both the equatorial and axial anion sites of Sr 2 Mn 0.5 Ir 0.5 O 2.66 H 1.33 . This highly unusual anion distribution is attributed to a combination of the strong trans -influence of Ir–H σ-bonds and the stabilization of fac -IrO 3 H 3 centers by spin–orbit coupling effects. Magnetization data indicate that Sr 2 Mn 0.5 Ir 0.5 O 4 and Sr 2 Mn 0.5 Ir 0.5 O 3.25 H 0.75 adopt spin glass states at low temperature, behavior which is attributable to the cation disorder in Sr 2 Mn 0.5 Ir 0.5 O 4 and the cation and anion disorder in Sr 2 Mn 0.5 Ir 0.5 O 3.25 H 0.75 . In contrast, magnetization data collected from Sr 2 Mn 0.5 Ir 0.5 O 2.66 H 1.33 show no evidence of any magnetic phase transition down to 5 K, consistent with the dilution of the magnetic network by the introduction of diamagnetic Ir 3+ on the formation of the oxyhydride phase.
Source: Inorganic Chemistry
Authors: James I. Murrell, Michael A. Hayward
Institution: University of Oxford
Language: English
Field: Materials Science
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,500
OpenAlex ID: W4404054531