For the reducing agent known as Superhydride, see Lithium triethylborohydride.
A polyhydride or superhydride is a compound that contains an abnormally large amount of hydrogen. This can be described as high hydrogen stoichiometry. Examples include iron pentahydride FeH5, LiH6, and LiH7. By contrast, the more well known lithium hydride only has one hydrogen atom.[1]
Polyhydrides are only known to be stable under high pressure.[1]
Polyhydrides are important because they can form substances with a very high density of hydrogen. They may resemble the elusive metallic hydrogen, but can be made under lower pressures. One possibility is that they could be superconductors. Hydrogen sulfide under high pressures forms SH3 units, and can be a superconductor at 203 K (−70 °C) and a pressure of 1.5 million atmospheres.[1]
^ abcPépin, C. M.; Geneste, G.; Dewaele, A.; Mezouar, M.; Loubeyre, P. (27 July 2017). "Synthesis of FeH5 : A layered structure with atomic hydrogen slabs". Science. 357 (6349): 382–385. Bibcode:2017Sci...357..382P. doi:10.1126/science.aan0961. PMID 28751605.
A polyhydride or superhydride is a compound that contains an abnormally large amount of hydrogen. This can be described as high hydrogen stoichiometry...
Lanthanum decahydride is a polyhydride or superhydride compound of lanthanum and hydrogen (LaH10) that has shown evidence of being a high-temperature...
Argon compounds, the chemical compounds that contain the element argon, are rarely encountered due to the inertness of the argon atom. However, compounds...
of the Scientific Council of IFPEN (from 2007 to 2011). B. Chaudret Polyhydrides and Nanoparticles: A 35 year Trip in Organometallic Chemistry Histoire...
Michael (1999). "Prediction of the Geometries of Simple Transition Metal Polyhydride Complexes by Symmetry Analysis". J. Am. Chem. Soc. 121 (6): 1348–1358...
Michael (1999). "Prediction of the Geometries of Simple Transition Metal Polyhydride Complexes by Symmetry Analysis". J. Am. Chem. Soc. 121 (6): 1348–1358...
always low-spin. Ir(III) and Ir(IV) generally form octahedral complexes. Polyhydride complexes are known for the +5 and +3 oxidation states. One example is...
hydride was retracted from Nature. CSH is an uncharacterized ternary polyhydride compound of carbon, sulfur and hydrogen with a chemical formula that...
is stable at pressures exceeding 65 GPa. Iron pentahydride FeH5 is a polyhydride, where there is more hydrogen than expected by valence rules. It is stable...
hydrides include the anions in Mg2FeH6 and Mg2NiH4. Some of these anionic polyhydrides satisfy the 18-electron rule, many do not. Because of their high lattice...
always low-spin. Ir(III) and Ir(IV) generally form octahedral complexes. Polyhydride complexes are known for the +5 and +3 oxidation states. One example is...
central atoms. These are very unstable but some have been shown to exist. Polyhydrides or superhydrides are compounds in which the number of hydrogen atoms...
yttrium hydrides are known at standard conditions, YH2 and YH3. YH9, a polyhydride is stable at high pressures, and is a superconductor at temperatures...
in free H2. Some complexes containing multiple hydrogen ligands, i.e. polyhydrides, also exhibit short H−H contacts. It has been suggested that distances...
21°C at a pressure of 1GPa, which is considerably lower than for other polyhydrides. This has been called "red matter" as it is red under high pressure,...
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