X-ray magnetic circular dichroism investigation of the superparamagnetic transition-metal ion-cluster r-Mn(12)Bz

We present the results of an X-ray magnetic circular dichroism investigation of a reduced version of Mn(12) benzoate. At variance with the parent Mn(12) benzoate compound, which, analogously to Mn(12) 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 Mn(12) benzoate. In particular, we performed multiplet calculations to analyse the X-ray magnetic circular dichroism spectra at the manganese L(2,3) edge and identify the contribution of the Mn(II) ion resulting by the reduction process.