Synthese und struktur von Li3RhH4, einem ternären hydrid mit planaren [RhH4]3--Baueinheiten

Bronger, W.; Müller, Paul; Kowalczyk, J.; Auffermann, Gudrun

doi:10.1016/0925-8388(91)90034-s

Cited by 23 publications

(23 citation statements)

References 4 publications

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“…The case of Li 3 RhH 4 Ref. [26] is more difficult. Assuming coordination numbers of six and seven for lithium atoms, [26] the full formula is Li(1) 2 [7] Li(2) [6] Rh [4]…”

Section: Complex Transition Metal Hydridesmentioning

confidence: 99%

Ion Segregation and Electrostatic Imbalance in Metal Hydrides

Voss

Kohlmann

2017

Zeitschrift anorg allge chemie

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Crystal chemical indices of ion segregation and electrostatic imbalance after Beck help to rationalize inorganic crystal structures and sometimes even to predict them. Metal hydrides, from hydridoaluminates and -gallates, to complex transition metal hydrides, ternary ionic magnesium hydrides and mixed anionic hydrides, were investigated using these tools. Beck's ion segregation and electrostatic imbalance indices are found to work well in explaining crystal structures of * Prof. Dr. H. Kohlmann

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“…The case of Li 3 RhH 4 Ref. [26] is more difficult. Assuming coordination numbers of six and seven for lithium atoms, [26] the full formula is Li(1) 2 [7] Li(2) [6] Rh [4]…”

Section: Complex Transition Metal Hydridesmentioning

confidence: 99%

Ion Segregation and Electrostatic Imbalance in Metal Hydrides

Voss

Kohlmann

2017

Zeitschrift anorg allge chemie

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“…Neutron absorption cross sections, σ a , for the natural isotopic mixtures for most elements are below 100 barn at λ = 179.8 pm for the majority of elements; for those between 100 and 1000 barn neutron diffraction on their compounds is severely impaired, and structure determination possible, but often impeded (for example, σ a (Rh) = 145 barn, e.g. in Li 3 RhH 4 , σ a (Dy) = 994 barn, e.g. in DyHO, and σ a (Ir) = 425 barn, e.g.…”

Section: Introductionmentioning

confidence: 99%

From SmOF to SmH_0.78OF_0.22: H/F Substitution in Oxide Fluorides as a Synthesis Route to Heteroanionic Compounds

2021

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Mixed anionic hydrides of the rare earths are a fascinating class of compounds as potential functional materials, especially in luminescence, as photochromic thin films and for ion conduction. For exploratory studies, the effectiveness of various synthesis methods must be investigated, which is done here for metathesis reactions. The reaction of Sm2O3 with PTFE yields SmOF (P21/c, a = 5.60133(19) Å, b = 5.65567(19) Å, c = 5.6282(2) Å, β = 90.169(5)°, V = 178.295(11) Å3, and Z = 4) in a new, probably metastable, polymorph of the baddeleyite-type structure. Metathesis reactions of SmOF with LiH, NaH, or CaH2 led to a samarium hydride oxide fluoride, SmH x OF1–x ; i.e., incomplete H/F exchange occurs. X-ray diffraction and neutron diffraction on a compound with x = 0.78 obtained via NaH reveal hydride, oxide, and fluoride ions to be partially ordered. SmH0.78OF0.22 (Ia3̅, a = 10.947(2) Å, V = 1311.7(4) Å3, Z = 32) crystallizes in an anti-Li3AlN2-type structure with distorted cubic anion coordination for samarium atoms (site symmetry 3̅ and 2) and distorted tetrahedral arrangement of samarium atoms around the anions (site symmetry 1 and 3). It is a fully structurally characterized hydride oxide fluoride and shows a rare crystal chemical featurethe occupation of a crystallographic site by three different anions (0.188 H + 0.667 O + 0.145 F). Interatomic distances between samarium and hydrogen and samarium and the mixed hydrogen/oxygen/fluorine site range from 2.45 to 2.48 Å and 2.29 to 2.42 Å, respectively, and are similar to those in samarium hydride, samarium oxide, and samarium fluoride. Fluoride extraction by reaction with alkali and alkaline earth hydrides has thus proven to be a useful synthesis route to hydride oxides and also hydride oxide halogenides, which might be further exploited in exploratory research on heteroanionic metal hydrides.

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“…This may be illustrated by ternary alkaline and alkaline earth rhodium hydrides. While rhodium does not form a binary hydride, several ternary hydrides are known, for example, typical semiconducting 18electron complex hydrides A 3 RhH 6 (A = Li, 5 Na 6 ) with isolated RhH 6 octahedra. Li 3 RhH 4 with reduced hydrogen content might be regarded at first sight as a typical 16 valenceelectron complex hydride.…”

Section: ■ Introductionmentioning

confidence: 99%

“…However, weak rhodium−rhodium interactions are noticed between the stacked square-planar RhH 4 units. 7 Stronger metal−metal bonding is found in MgRhH 1−x , where Rh−H and significant Rh−Rh interactions prevail. 8,9 The latter might be weakened by exchanging magnesium by the higher homologue calcium due to the higher space requirement as suggested by density functional theory (DFT) calculations.…”

Section: ■ Introductionmentioning

confidence: 99%

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From the Laves Phase CaRh₂ to the Perovskite CaRhH₃–in Situ Investigation of Hydrogenation Intermediates CaRh₂H_x

2018

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The hydrogenation properties of the cubic Laves phase CaRh and the formation of the perovskite CaRhH were studied by in situ thermal analysis (differential scanning calorimetry), sorption experiments, and in situ neutron powder diffraction. Three Laves phase hydrides are formed successively at room temperature and hydrogen gas pressures up to 5 MPa. Cubic α-CaRhH is a stuffed cubic Laves phase with statistically distributed hydrogen atoms in tetrahedral [CaRh] voids (ZrCrH type, Fd3̅ m, a = 7.5308(12) Å). Orthorhombic β-CaRhD (own structure type, Pnma, a = 6.0028(3) Å, b = 5.6065(3) Å, c = 8.1589(5) Å) and γ-CaRhD (β-CaRhH type, Pnma, a = 5.9601(10) Å, b = 5.4912(2) Å, c = 8.0730(11) Å) are low-symmetry variants thereof with hydrogen occupying distorted tetrahedral [CaRh] and trigonal bipyramidal [CaRh] voids. Hydrogen sorption experiments show the hydrogenation to take place already at 0.1 MPa and to yield β-CaRhH. At 560 K and 5 MPa hydrogen pressure the Laves phase hydride decomposes kinetically controlled to nanocrystalline rhodium and CaRhD (CaTiO type, Pm3̅ m, a = 3.6512(2) Å). The hydrogenation of CaRh provides a synthesis route to otherwise not accessible perovskite-type CaRhH.

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Synthese und struktur von Li3RhH4, einem ternären hydrid mit planaren [RhH4]3--Baueinheiten

Cited by 23 publications

References 4 publications

Ion Segregation and Electrostatic Imbalance in Metal Hydrides

Ion Segregation and Electrostatic Imbalance in Metal Hydrides

From SmOF to SmH_0.78OF_0.22: H/F Substitution in Oxide Fluorides as a Synthesis Route to Heteroanionic Compounds

From the Laves Phase CaRh₂ to the Perovskite CaRhH₃–in Situ Investigation of Hydrogenation Intermediates CaRh₂H_x

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Synthese und struktur von Li3RhH4, einem ternären hydrid mit planaren [RhH4]3--Baueinheiten

Cited by 23 publications

References 4 publications

Ion Segregation and Electrostatic Imbalance in Metal Hydrides

Ion Segregation and Electrostatic Imbalance in Metal Hydrides

From SmOF to SmH0.78OF0.22: H/F Substitution in Oxide Fluorides as a Synthesis Route to Heteroanionic Compounds

From the Laves Phase CaRh2 to the Perovskite CaRhH3–in Situ Investigation of Hydrogenation Intermediates CaRh2Hx

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From SmOF to SmH_0.78OF_0.22: H/F Substitution in Oxide Fluorides as a Synthesis Route to Heteroanionic Compounds

From the Laves Phase CaRh₂ to the Perovskite CaRhH₃–in Situ Investigation of Hydrogenation Intermediates CaRh₂H_x