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Structural and Electronic Characterization of Eu 2 LiSi 3 , Eu 2 LiGe 3 and Eu x Sr 2−x LiGe 3 Mixed Crystals
Author(s) -
Xie Qinxing,
Nesper Reinhard
Publication year - 2006
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.200600118
Subject(s) - crystallography , electron localization function , ion , crystal structure , chemistry , electronic structure , mulliken population analysis , materials science , computational chemistry , density functional theory , electron , physics , organic chemistry , quantum mechanics
The new rare earth metal Zintl phases Eu 2 LiSi 3 , Eu 2 LiGe 3 and the solid solution Eu x Sr 4−x Li 2 Ge 6 have been synthezised by solid state inert gas techniques and their crystal structures been determined from single crystals. Eu 2 LiSi 3 crystallizes in an own structure type which has close relations to the ThSi 2 type with lithium being situated on silicon vacancies. This generates a new kind of planar Zintl anion which has an all trans linear chain backbone and terminal Si side groups at half of the silicon atoms of the chain. Eu 2 LiGe 3 forms the α−Ca 2 LiSi 3 structure with an unbranched planar polymeric Zintl anion which has a cis‐trans conformation of the kind (tttctc) n . Both of the polyanions [Si 3 ] 5− and [Ge 3 ] 5− , respectively are unsaturated with an underoccupied π* system leaving one residual π bond per three Tt atoms (Tt = Si, Ge). Features of the crystal and of the electronic structures are being analysed based on geometrical and on band structure considerations. DOS, partial DOS, Mulliken overlap populations and calculations of the electron localization function (ELF) based on Extended Hückel and on LMTO calculations confirm the bonding structure and reveal preferred localizations of the π bonds.