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Origin of the Paramagnetic Properties of the Mixed‐Valence Polyoxometalate [GeV 14 O 40 ] 8– Reduced by Two Electrons: Wave Function Theory and Model Hamiltonian Calculations
Author(s) -
Suaud N.,
Masaro Y.,
Coronado E.,
ClementeJuan J. M.,
Guihéry N.
Publication year - 2009
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200900803
Subject(s) - chemistry , unpaired electron , polyoxometalate , delocalized electron , valence (chemistry) , electron , valence electron , atomic physics , wave function , hamiltonian (control theory) , exchange interaction , paramagnetism , electron transfer , electron paramagnetic resonance , condensed matter physics , nuclear magnetic resonance , physics , ferromagnetism , molecule , quantum mechanics , mathematical optimization , biochemistry , mathematics , organic chemistry , catalysis
The aim of the work is to give an explanation of the magnetic properties of a mixed‐valence [GeV 14 O 40 ] 8– polyoxometalate reduced by two electrons, which, in contrast to what happens in other two‐electron‐reduced polyoxometalates, does not show any magnetic coupling between the two unpaired electrons. For this purpose, a quantitative evaluation of the microscopic electronic parameters (electron transfer, magnetic coupling, magnetic orbital energy, and Coulomb repulsion) of the mixed‐valence polyoxometalate cluster is performed. The parameters are extracted from valence‐spectroscopy large configuration interaction (CI) calculations on embedded fragments. Then, these parameters are used in an extended t ‐ J model Hamiltonian suited to model the properties of the whole anion. The analysis of the wave functions of the lowest singlet and triplet states and of the microscopic parameters emphasizes that the electron delocalization in this mixed‐valence cluster is such that each unpaired electron is almost trapped in a different half of the polyoxovanadate, thus disabling any exchange interaction between them.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)