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Unconventional Metal–Framework Interaction in MgSi 5
Author(s) -
Hübner JuliaMaria,
CarrilloCabrera Wilder,
Prots Yurii,
Bobnar Matej,
Schwarz Ulrich,
Grin Yuri
Publication year - 2019
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201907432
Subject(s) - silicon , crystallography , lone pair , group (periodic table) , materials science , diffraction , crystal structure , center (category theory) , chemistry , molecule , metallurgy , physics , optics , organic chemistry
The silicon‐rich cage compound MgSi 5 was obtained by high‐pressure high‐temperature synthesis. Initial crystal structure determination by electron diffraction tomography provided the basis for phase analyses in the process of synthesis optimization, finally facilitating the growth of single crystals suitable for X‐ray diffraction experiments. The crystal structure of MgSi 5 (space group Cmme , Pearson notation oS 24, a= 4.4868(2) Å, b= 10.1066(5) Å, and c =9.0753(4) Å) constitutes a new type of framework of four‐bonded silicon atoms forming Si 15 cages enclosing the Mg atoms. Two types of smaller Si 8 cages remain empty. The atomic interactions are characterized by two‐center two‐electron bonds within the silicon framework. In addition, there is evidence for multi‐center Mg−Si bonding in the large cavities of the framework and for lone‐pair‐like interactions in the smaller empty voids.