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Na 4 IrO 4 : Square‐Planar Coordination of a Transition Metal in d 5 Configuration due to Weak On‐Site Coulomb Interactions
Author(s) -
Kanungo Sudipta,
Yan Binghai,
Merz Patrick,
Felser Claudia,
Jansen Martin
Publication year - 2015
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201411959
Subject(s) - coulomb , valence (chemistry) , chemistry , electronic correlation , planar , electron , electronic structure , valence electron , transition metal , ground state , electron configuration , square (algebra) , crystallography , cuprate , condensed matter physics , coordination geometry , center (category theory) , metal , ab initio , atomic physics , physics , computational chemistry , geometry , molecule , quantum mechanics , computer graphics (images) , biochemistry , organic chemistry , mathematics , doping , computer science , catalysis , hydrogen bond
Local environments and valence electron counts primarily determine the electronic states and physical properties of transition‐metal complexes. For example, square‐planar coordination geometries found in transition‐metal oxometalates such as cuprates are usually associated with the d 8 or d 9 electron configuration. In this work, we address an unusual square‐planar single oxoanionic [IrO 4 ] 4− species, as observed in Na 4 IrO 4 in which Ir IV has a d 5 configuration, and characterize the chemical bonding through experiments and by ab initio calculations. We find that the Ir IV center in ground‐state Na 4 IrO 4 has square‐planar coordination geometry because of the weak Coulomb repulsion of the Ir‐5d electrons. In contrast, in its 3d counterpart Na 4 CoO 4 , the Co IV center is tetrahedrally coordinated because of strong electron correlation. Na 4 IrO 4 may thus serve as a simple yet important example to study the ramifications of Hubbard‐type Coulomb interactions on local geometries.