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Ligand field theoretical considerations

Published in Topics in current chemistry. Vol. 233 : Spin crossover in transition metal compounds I: Springer. 2004, p. 49-58
Abstract The phenomenon of the thermal spin transition, as observed for octahedral transition metal complexes having a d 4 to d 7 electronic configuration, can be fully rationalised on the basis of ligand field theory. In order to arrive at a self-consistent description of the vibronic structure of spin crossover compounds, it is essential to take into account the fact that the population of anti-bonding orbitals in the high-spin state results in a substantially larger metal-ligand bond length than for the low-spin state. Whereas the electron-electron repulsion is not affected to any great extent by such a bond length difference, the ligand field strength for iron(II) spin crossover compounds can be estimated to be almost twice as large in the low-spin state as compared to the one for the high-spin state. In fact, the dependence of the ligand field strength on the metal-ligand distance may be considered the quantum mechanical driving force for the spin crossover phenomenon.
Keywords Spin crossoverLigand field theoryOptical propertiesVibronic structureConfigurational coordinate
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HAUSER, Andreas. Ligand field theoretical considerations. In: Topics in current chemistry. Vol. 233 : Spin crossover in transition metal compounds I. [s.l.] : Springer, 2004. p. 49-58. doi: 10.1007/b13528 https://archive-ouverte.unige.ch/unige:3942

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Deposited on : 2009-10-30

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