Magnetic Properties of Spin-crossover Systems in Iron(III) Thioseleno- and Diselenocarbamates

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Effect of dilution in the corresponding cobalt(III) or indium(III) complex matrices on EPR spectra


The temperature-dependent magnetic moments between 8 and 310 K have been measured for a series of iron(III) tris-thioselenocarbamates, Fe(SSeCNR2)3, where NR2 is N(CH2C6H5)2, N(CH2)4, N(CH2)5, N(CH2)4O or N(C6H11)2. Whereas the dibenzyl, piperidyl and morpholyl derivatives clearly show spin-crossover behavior at room temperature reaching the low-spin state near liquid nitrogen temperature, the dicyclohexyl derivative is in the pure low-spin state at all temperatures measured. The pyrrolidyl complex, mainly high spin at higher temperatures, exhibits substantial spin-crossover behavior even at 8 K. The EPR powder spectra of the iron(III) tris-thioselenocarbamates, diluted (1:99%) with the corresponding cobalt(III) or indium(III) tris-thioselenocarbamate have been recorded between 120 K and room temperature. These spectra can be used as fingerprints to study qualitatively the influences of temperature and matrix effects on the electronic configuration of spin-crossover systems. In most cases they exhibit a relatively narrow signal at g ≈ 2 and two broad signals with g ≈ 4 and g ≈ 2 which have been attributed to the S=1/2 and S=5/2 state, respectively. Spectra for the corresponding tris- diselenocarbamates are also included and correlated. © 1990.



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© 1990 Elsevier, All rights reserved.