, Volume 219, Issue 1-3, pp 77-82
Date: 16 Nov 2012

Magnetic and Mössbauer spectra observed for mixed-metal magnets NBu4 \({\bf Fe}^{\bf II}_{\bf n}\) MA II 1 − n [FeIII(OX)3] (MA=Mn, Fe)

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Abstract

Mixed-metal molecular-based magnets NBu4 \({\rm Fe}^{\rm II}_{\rm n}\) MA II 1 − n[FeIII(OX)3] (MA=Mn, Fe) were investigated by magnetic and Mössbauer measurements. The magnetic susceptibility of NBu4 \({\rm Fe}^{\rm II}_{0.07}{\rm Mn}^{\rm II}_{0.93}\) [FeIII(OX)3] can be fitted to a Curie-Weiss law with a Weiss paramagnetic Curie temperature of θ = −114.76 K. The negative Weiss constant indicates an intramolecular antiferromagnetic coupling interaction between the adjacent Fe(II) and Fe(III) ions through the oxalate bridge. In the complex NBu4FeII[FeIII(OX)3], the Mössbauer results indicate that the FeII and FeIII sublattices experience spontaneous magnetizations. The compound contains two different spin carriers; i.e. FeII(S = 2), FeIII(S = 5/2). Two magnetic sublattices are defined. The appearance of nuclear Zeeman splittings suggests that long range magnetic ordering takes place below 50 K.