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

Siméon Ponou; Sven Lidin; Anja Verena Mudring

doi:10.1021/acs.inorgchem.2c04312

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

Siméon Ponou, Sven Lidin, Anja Verena Mudring^*

^*Corresponding author af dette arbejde

Publikation: Bidrag til tidsskrift/Konferencebidrag i tidsskrift /Bidrag til avis › Tidsskriftartikel › Forskning › peer review

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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 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.

Originalsprog	Engelsk
Tidsskrift	Inorganic Chemistry
Vol/bind	62
Nummer	22
Sider (fra-til)	8519-8529
ISSN	0020-1669
DOI	https://doi.org/10.1021/acs.inorgchem.2c04312
Status	Udgivet - jun. 2023

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10.1021/acs.inorgchem.2c04312Licens: CC BY

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Citationsformater

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title = "Optimization of Chemical Bonding through Defect Formation and Ordering-The Case of Mg7Pt4Ge4",

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 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.",

author = "Sim{\'e}on Ponou and Sven Lidin and Mudring, {Anja Verena}",

note = "Publisher Copyright: {\textcopyright} 2023 The Authors. Published by American Chemical Society.",

year = "2023",

month = jun,

doi = "10.1021/acs.inorgchem.2c04312",

language = "English",

volume = "62",

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T1 - Optimization of Chemical Bonding through Defect Formation and Ordering-The Case of Mg7Pt4Ge4

AU - Ponou, Siméon

AU - Lidin, Sven

AU - Mudring, Anja Verena

PY - 2023/6

Y1 - 2023/6

N2 - 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.

AB - 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.

U2 - 10.1021/acs.inorgchem.2c04312

DO - 10.1021/acs.inorgchem.2c04312

M3 - Journal article

C2 - 37207284

AN - SCOPUS:85162269988

SN - 0020-1669

VL - 62

SP - 8519

EP - 8529

JO - Inorganic Chemistry

JF - Inorganic Chemistry

IS - 22

ER -

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

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