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[Ge 2 ] 4− Dumbbells with Very Short Ge−Ge Distances in the Zintl Phase Li 3 NaGe 2 : A Solid‐State Equivalent to Molecular O 2
Author(s) -
Scherf Lavinia M.,
Karttunen Antti J.,
Pecher Oliver,
Magusin Pieter C. M. M.,
Grey Clare P.,
Fässler Thomas F.
Publication year - 2016
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201508044
Subject(s) - zintl phase , crystallography , chemistry , dumbbell , atomic orbital , alkali metal , germanide , ternary operation , germanium , raman spectroscopy , crystal structure , physics , electron , silicon , organic chemistry , optics , physical therapy , medicine , quantum mechanics , computer science , programming language
Abstract The novel ternary Zintl phase Li 3 NaGe 2 comprises alkali‐metal cations and [Ge 2 ] 4− dumbbells. The diatomic [Ge 2 ] 4− unit is characterized by the shortest Ge−Ge distance (2.390(1) Å) ever observed in a Zintl phase and thus represents the first Ge=Ge double bond under such conditions, as also suggested by the (8− N ) rule. Raman measurements support these findings. The multiple‐bond character is confirmed by electronic‐structure calculations, and an upfield 6 Li NMR shift of −10.0 ppm, which was assigned to the Li cations surrounded by the π systems of three Ge dumbbells, further underlines this interpretation. For the unperturbed, ligand‐free dumbbell in Li 3 NaGe 2 , the π‐ bonding p y and p z orbitals are degenerate as in molecular oxygen, which has singly occupied orbitals. The partially filled π‐type bands of the neat solid Li 3 NaGe 2 cross the Fermi level, resulting in metallic properties. Li 3 NaGe 2 was synthesized from the elements as well as from binary reactants and subsequently characterized crystallographically.