A Strongly Spin‐Frustrated FeIII7 Complex with a Canted Intermediate Spin Ground State of S=7/2 or 9/2 |
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| Authors: | Dr Kartik Chandra Mondal Dr Valeriu Mereacre Dr George E Kostakis Dr Yanhua Lan Dr Christopher E Anson Dr Ion Prisecaru Prof?Dr Oliver Waldmann Prof?Dr Annie K Powell |
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| Institution: | 1. Institut für Anorganische Chemie, Karlsruher Institut für Technologie, Engesserstr. 15, 76131 Karslruhe (Germany);2. Institut für Nanotechnologie, Karlsruher Institut für Technologie, Herrmann‐von‐Helmholtz‐Platz 1, 76344 Eggenstein‐Leopoldshafen (Germany);3. WMOSS.ORG, Max‐Beckmann‐Str. 29, 76227, Karlsruhe (Germany);4. Physikalisches Institut, Universit?t Freiburg, Hermann‐Herder‐Strasse 3, 79104 Freiburg (Germany) |
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| Abstract: | A disk‐shaped FeIII7(Cl)(MeOH)6(μ3‐O)3(μ‐OMe)6 (PhCO2)6]Cl2 complex with C3 symmetry has been synthesised and characterised. The central tetrahedral FeIII is 0.733 Å above the almost co‐planar FeIII6 wheel, to which it is connected through three μ3‐oxide bridges. For this iron‐oxo core, the magnetic susceptibility analysis proposed a Heisenberg–Dirac–van Vleck (HDvV) mechanism that leads to an intermediate spin ground state of S=7/2 or 9/2. Within either of these ground state manifolds it is reasonable to expect spin frustration effects. The 57Fe Mössbauer (MS) analysis verifies that the central FeIII ion easily aligns its magnetic moment antiparallel to the externally applied field direction, whereas the other six peripheral FeIII ions keep their moments almost perpendicular to the field at stronger fields. This unusual canted spin structure reflects spin frustration. The small linewidths in the magnetic Mössbauer spectra of polycrystalline samples clearly suggest an isotropic exchange mechanism for realisation of this peculiar spin topology. |
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| Keywords: | magnetic properties Mö ssbauer spectroscopy polynuclear iron complexes spin frustration |
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