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Issue 16, 2007
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The spin coupling in the diiron complex [Fe2(hpdta)(H2O)3Cl]

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Density functional, multireference configuration interaction, and modified valence configuration interaction calculations are used to investigate the electronic structure and spin coupling of the dinuclear [Fe2(hpdta)(H2O)3Cl] complex (H5hpdta = Hydroxypropane-1,3-diamine-N,N,N′,N′-tetraacetic acid). The density functional calculations give evidence of both, states with local high-spin iron centres and states with local low-spin iron centres, the relative energy of which strongly depends on the functional. The splitting of states due to the spin coupling between the high-spin iron centres varies by more than a factor of two for different functionals. In an attempt to study to what extent it is possible to undertake configuration interaction calculations on such binuclear compounds, multireference configuration interaction calculations are performed on a [Fe2(OH)5(H2O)3(NH3)2Cl] model complex. The results show that, when correlating only the ten iron 3d orbitals and the four valence orbitals of the bridging OH group, the calculated splitting is still by a factor of about 3 smaller than the value for the splitting inferred from magnetic susceptibility measurements. Modified valence configuration interaction calculations are performed to approximately take into account the influence of orbital relaxation effects of all occupied orbitals in the excited configurations. The exchange splitting is significantly increased, but still smaller than the experimental value.

Graphical abstract: The spin coupling in the diiron complex [Fe2(hpdta)(H2O)3Cl]

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Article information

04 Dec 2006
15 Jan 2007
First published
12 Feb 2007

Phys. Chem. Chem. Phys., 2007,9, 1911-1920
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The spin coupling in the diiron complex [Fe2(hpdta)(H2O)3Cl]

O. Hübner, K. Fink and W. Klopper, Phys. Chem. Chem. Phys., 2007, 9, 1911
DOI: 10.1039/B617670D

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