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A Position‐Space View on Chemical Bonding in Metal Diborides with AlB 2 Type of Crystal Structure
Author(s) -
Wagner Frank R.,
Baranov Alexey I.,
Grin Yuri,
Kohout Miroslav
Publication year - 2013
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.201200523
Subject(s) - crystallography , delocalized electron , chemical bond , group (periodic table) , covalent bond , crystal (programming language) , chemistry , metal , transition metal , materials science , biochemistry , organic chemistry , computer science , programming language , catalysis
On the basis of QTAIM and ELI‐D partitioning of position space two‐ and three‐center delocalization indices were calculated for fifteen M B 2 phases with the crystal structure of AlB 2 type. The bonding picture in main‐group metal diborides is closest related to graphite with dominant covalent B–B bonding, albeit with lower effective bond order. For MgB 2 an exceptionally large distant electron sharing was found. Transition‐metal diborides display smaller effective bond orders B–B but higher effective bond orders TM –B and TM – TM than main‐group metal diborides. The large chemical flexibility of this structure type is caused by counterbalancing effects of B–B bonding vs. M –B and M – M bonding. Different three‐center fluctuation channels of bonds B–B are found for main‐group and transition‐metal diborides, namely B–B–B for the former and B–B– M for the latter. With the technique of ELI‐D/QTAIM intersection the increasing importance of B 2 →4 M bond charge fluctuations along each row of the periodic table can be recovered already at the topological level of analysis.