ISSN:
1572-9540
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract 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 distancesd Fe-Mn=0.35 nm andd Fe-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=J Fe-Mn(S Fe1+S Fe2)S Mn +J Fe-Fe(S Fe1 S Fe2) +gΜB S total B. The spinsS Fe1=S Fe2 =S Mn=5/2 of the complex are antiferromagnetically coupled, yielding a total spin ofS total=5/2 with exchange coupling constantsF Fe-Mn=13.4 cm−1 andJ Fe-Fe= 4.5 cm−1. Magnetically split Mössbauer spectra were recorded at 1.5 K under various applied fields (20 mT, 170 mT, 4T). The spin-Hamiltonian analysis of these spectra yields isotropic magnetic hyperfine coupling withA total/(g N Μ N)=−18.5 T. The corresponding local componentA Fe is related toA total via spin-projection:A total=(6/7)AFe. The resultingA Fe/(g NΜN)=−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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02063706
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