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Optimization of Chemical Bonding through Defect Formation and Ordering-The Case of Mg7Pt4Ge4

Ponou, Siméon LU ; Lidin, Sven LU and Mudring, Anja Verena (2023) In Inorganic Chemistry 62(22). p.8519-8529
Abstract

The new phase Mg7Pt4Ge4 (Mg8□1Pt4Ge4; □ = vacancy) was prepared by reacting a mixture of the corresponding elements at high temperatures. According to single crystal X-ray diffraction data, it adopts a defect variant of the lighter analogue Mg2PtSi (Mg8Pt4Si4), reported in the Li2CuAs structure. An ordering of the Mg vacancies results in a stoichiometric phase, Mg7Pt4Ge4. However, the high content of Mg vacancies results in a violation of the 18-valence electron rule, which appears to hold for Mg2PtSi. First principle density functional theory calculations on a hypothetical, vacancy-free "Mg2PtGe"reveal potential electronic instabilities at EF in the band structure and significant occupancy of states with an antibonding character... (More)

The new phase Mg7Pt4Ge4 (Mg8□1Pt4Ge4; □ = vacancy) was prepared by reacting a mixture of the corresponding elements at high temperatures. According to single crystal X-ray diffraction data, it adopts a defect variant of the lighter analogue Mg2PtSi (Mg8Pt4Si4), reported in the Li2CuAs structure. An ordering of the Mg vacancies results in a stoichiometric phase, Mg7Pt4Ge4. However, the high content of Mg vacancies results in a violation of the 18-valence electron rule, which appears to hold for Mg2PtSi. First principle density functional theory calculations on a hypothetical, vacancy-free "Mg2PtGe"reveal potential electronic instabilities at EF in the band structure and significant occupancy of states with an antibonding character resulting from unfavorable Pt-Ge interactions. These antibonding interactions can be eliminated through introduction of Mg defects, which reduce the valence electron count, leaving the antibonding states empty. Mg itself does not participate in these interactions. Instead, the Mg contribution to the overall bonding comes from electron back-donation from the (Pt, Ge) anionic network to Mg cations. These findings may help to understand how the interplay of structural and electronic factors leads to the "hydrogen pump effect"observed in the closely related Mg3Pt, for which the electronic band structure shows a significant amount of unoccupied bonding states, indicating an electron deficient system.

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author
; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Inorganic Chemistry
volume
62
issue
22
pages
11 pages
publisher
The American Chemical Society (ACS)
external identifiers
  • pmid:37207284
  • scopus:85162269988
ISSN
0020-1669
DOI
10.1021/acs.inorgchem.2c04312
language
English
LU publication?
yes
id
8578977a-cc5b-4ab1-a386-a1104bf36a50
date added to LUP
2023-09-15 12:05:53
date last changed
2024-04-19 00:54:04
@article{8578977a-cc5b-4ab1-a386-a1104bf36a50,
  abstract     = {{<p>The new phase Mg7Pt4Ge4 (Mg8□1Pt4Ge4; □ = vacancy) was prepared by reacting a mixture of the corresponding elements at high temperatures. According to single crystal X-ray diffraction data, it adopts a defect variant of the lighter analogue Mg2PtSi (Mg8Pt4Si4), reported in the Li2CuAs structure. An ordering of the Mg vacancies results in a stoichiometric phase, Mg7Pt4Ge4. However, the high content of Mg vacancies results in a violation of the 18-valence electron rule, which appears to hold for Mg2PtSi. First principle density functional theory calculations on a hypothetical, vacancy-free "Mg2PtGe"reveal potential electronic instabilities at EF in the band structure and significant occupancy of states with an antibonding character resulting from unfavorable Pt-Ge interactions. These antibonding interactions can be eliminated through introduction of Mg defects, which reduce the valence electron count, leaving the antibonding states empty. Mg itself does not participate in these interactions. Instead, the Mg contribution to the overall bonding comes from electron back-donation from the (Pt, Ge) anionic network to Mg cations. These findings may help to understand how the interplay of structural and electronic factors leads to the "hydrogen pump effect"observed in the closely related Mg3Pt, for which the electronic band structure shows a significant amount of unoccupied bonding states, indicating an electron deficient system.</p>}},
  author       = {{Ponou, Siméon and Lidin, Sven and Mudring, Anja Verena}},
  issn         = {{0020-1669}},
  language     = {{eng}},
  number       = {{22}},
  pages        = {{8519--8529}},
  publisher    = {{The American Chemical Society (ACS)}},
  series       = {{Inorganic Chemistry}},
  title        = {{Optimization of Chemical Bonding through Defect Formation and Ordering-The Case of Mg<sub>7</sub>Pt<sub>4</sub>Ge<sub>4</sub>}},
  url          = {{http://dx.doi.org/10.1021/acs.inorgchem.2c04312}},
  doi          = {{10.1021/acs.inorgchem.2c04312}},
  volume       = {{62}},
  year         = {{2023}},
}