Spektor K, Crichton WA, Filippov S, Simak SI, Fischer A, Häussermann U. Na
3FeH
7 and Na
3CoH
6: Hydrogen-Rich First-Row Transition Metal Hydrides from High Pressure Synthesis.
Inorg Chem 2020;
59:16467-16473. [PMID:
33141575 PMCID:
PMC7672699 DOI:
10.1021/acs.inorgchem.0c02294]
[Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
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The
formation of ternary hydrogen-rich hydrides involving the first-row
transition metals TM = Fe and Co in high oxidation states is demonstrated
from in situ synchrotron diffraction studies of reaction mixtures
NaH–TM–H2 at p ≈ 10
GPa. Na3FeH7 and Na3CoH6 feature pentagonal bipyramidal FeH73– and octahedral CoH63– 18-electron complexes,
respectively. At high pressure, high temperature (300 < T ≤ 470 °C) conditions, metal atoms are arranged
as in the face-centered cubic Heusler structure, and ab initio molecular
dynamics simulations suggest that the complexes undergo reorientational
dynamics. Upon cooling, subtle changes in the diffraction patterns
evidence reversible and rapid phase transitions associated with ordering
of the complexes. During decompression, Na3FeH7 and Na3CoH6 transform to tetragonal and orthorhombic
low pressure forms, respectively, which can be retained at ambient
pressure. The discovery of Na3FeH7 and Na3CoH6 establishes a consecutive series of homoleptic
hydrogen-rich complexes for first-row transition metals from Cr to
Ni.
In situ synchrotron diffraction studies
of reaction mixtures NaH−TM−H2 (TM = Fe,
Co) at p ≈ 10 GPa revealed the formation of
ternary hydrides Na3FeH7 and Na3CoH6 featuring pentagonal bipyramidal Fe(IV)H73− and octahedral Co(III)H63− complexes, respectively. The discovery of Na3FeH7 and Na3CoH6 establishes a consecutive
series of homoleptic hydrogen-rich complexes for first-row transition
metals from Cr to Ni.
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