Molecular magnetism of a linear Fe(III)-Mn(II)-Fe(III) complex. Influence of long-range exchange interaction

M. Lengen*, E. Bill, C. Butzlaff, A. X. Trautwein, M. Winter, P. Chaudhuri

*Corresponding author for this work
3 Citations (Scopus)


The magnetic properties of [L-Fe(III)-dmg3Mn(II)-Fe(III)-L] (ClO4)2 have been characterized by magnetic susceptibility, EPR, and Mössbauer studies. L represents 1,4,7-trimethyl-, 1,4,7-triazacyclononane and dmg represents dimethylglyoxime. X-ray diffraction measurements yield that the arrangement of the three metal centers is strictly linear with atomic distances dFe-Mn=0.35 nm and dFe-Fe=0.7 nm. Magnetic susceptibility measurements (3-295 K) were analyzed in the framework of the spin-Hamiltonian formalism considering Heisenberg exchange and Zeeman interaction:Ĥ=JFe-Mn(SFe1+SFe2)SMn +JFe-Fe(SFe1SFe2) +gΜBStotalB. The spins SFe1=SFe2 =SMn=5/2 of the complex are antiferromagnetically coupled, yielding a total spin of Stotal=5/2 with exchange coupling constants FFe-Mn=13.4 cm-1 and JFe-Fe= 4.5 cm-1. Magnetically split Mössbauer spectra were recorded at 1.5 K under various applied fields (20 m T, 170 mT, 4T). The spin-Hamiltonian analysis of these spectra yields isotropic magnetic hyperfine coupling with Atotal/(gNΜN)=-18.5 T. The corresponding local component AFe is related to Atotal via spin-projection:Atotal=(6/7)AFe. The resulting AFe/(gNΜN)=-21.6 T is in agreement with standard values of ferric high-spin complexes. Spin-Hamiltonian parameters as obtained from Mössbauer studies and exchange coupling constants as derived from susceptibility measurements are corroborated by temperature-dependent EPR studies.

Original languageEnglish
JournalHyperfine Interactions
Issue number1
Pages (from-to)1849-1853
Number of pages5
Publication statusPublished - 01.12.1994


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