X-ray magnetic circular dichroism investigation of the superparamagnetic transition-metal ion-cluster r-Mn12Bz

We present the results of an X-ray magnetic circular dichroism investigation of a reduced version of Mn12 benzoate. At variance with the parent Mn12 benzoate compound, which, analogously to Mn12 acetate, has a ground-state spin equal to ten, the reduced species has a ground-state with total spin S = 19/2. The half-integer spin in the ground-state makes this compound an appealing system where to test parity effects on the efficiency of the quantum tunnelling of the magnetisation. We exploited the sensitivity of X-ray magnetic circular dichroism to the oxidation state of the absorbing metal ion to obtain information about the internal structure of the reduced Mn12 benzoate. In particular, we performed multiplet calculations to analyse the X-ray magnetic circular dichroism spectra at the manganese L2,3 edge and identify the contribution of the MnII ion resulting by the reduction process.

X-ray magnetic circular dichroism (XMCD) has been used to assess the internal structure of a one-electron reduced version of Mn12 benzoate. The identification of the contribution of the MnII ion to the XMCD spectra allows to conclude that the MnIIMn7IIIMn4IV trapped-valence picture is appropriate in describing the valence state of the Mn ions comprising the magnetic core of the reduced Mn12Bz.Figure optionsDownload as PowerPoint slide