Premium
Stabilization of Highest‐Oxidation States of Transition Metals and the Induced Electronic Phenomena in Oxidic Perovskite Structures
Author(s) -
Demazeau Gérard
Publication year - 2005
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.200400437
Subject(s) - disproportionation , covalent bond , perovskite (structure) , transition metal , electronic structure , materials science , crystallography , condensed matter physics , chemical physics , anisotropy , chemistry , computational chemistry , catalysis , physics , biochemistry , organic chemistry , quantum mechanics
In oxides the stabilization of the highest oxidation states n+ of transition metals leads to the stabilization of strong covalent M n+ ‐O bonds. Such very covalent bonds can induce electronic phenomena as spin transitions through the increase of the local crystal‐field energy (Dq) or in the specific case of an anisotropic eg 1 electronic configuration some strong interactions with the perovskite structure (3D character, structural distortion…) can lead to a insulator→metal transition or a disproportionation phenomenon. [2M n+ ⇔(M (n—ϵ)+ )+(M (n+ϵ)+ )] In order to illustrate such a topic, three unusual oxidation states have been selected: Co 3+ (d 6 ), Fe 4+ (d 4 ) and Ni 3+ (d 7 ) in perovskite‐type structures.