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A Strongly Spin‐Frustrated Fe III 7 Complex with a Canted Intermediate Spin Ground State of S =7/2 or 9/2
Author(s) -
Mondal Kartik Chandra,
Mereacre Valeriu,
Kostakis George E.,
Lan Yanhua,
Anson Christopher E.,
Prisecaru Ion,
Waldmann Oliver,
Powell Annie K.
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201500841
Subject(s) - ground state , frustration , condensed matter physics , spin (aerodynamics) , spin states , spin structure , chemistry , magnetic moment , heisenberg model , physics , ferromagnetism , atomic physics , antiferromagnetism , thermodynamics
A disk‐shaped [Fe III 7 (Cl)(MeOH) 6 (μ 3 ‐O) 3 (μ‐OMe) 6 (PhCO 2 ) 6 ]Cl 2 complex with C 3 symmetry has been synthesised and characterised. The central tetrahedral Fe III is 0.733 Å above the almost co‐planar Fe III 6 wheel, to which it is connected through three μ 3 ‐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 57 Fe Mössbauer (MS) analysis verifies that the central Fe III ion easily aligns its magnetic moment antiparallel to the externally applied field direction, whereas the other six peripheral Fe III 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.