Reto Basler, Andreas Sieber, Grégory Chaboussant, Hans U. Güdel, Nicole E. Chakov, Monica Soler, George Christou, Arnaud Desmedt and Ruep Lechner
Inelastic Neutron Scattering Study of Electron Reduction in Mn₁₂ Derivatives
Inorg. Chem. 44, 649-453 (2005)                 

Abstract: We report inelastic neutron scattering (INS) studies on a series of Mn₁₂ derivatives, [Mn₁₂O₁₂(O₂CC₆F₅)₁₆(H₂O)₄]^z, in which the number of unpaired electrons in the cluster is varied. We investigated three oxidation levels: z = 0 for the neutral complex, z = -1 for the one-electron reduced species and z = -2 for the two-electron reduced complex. For z = 0, the ground state is S = 10 as in the prototypical Mn₁₂-acetate. For z = -1, we have S = ¹⁹/₂, and for z = - 2, an S = 10 ground state is retrieved. INS studies show that the axial zero-field splitting parameter D is strongly suppressed upon successive electron reduction: D = -0.45 cm^–1 (z = 0), D = -0.35 cm^–1 (z = -1), and D -0.26 cm^–1 (z = -2). Each electron reduction step is directly correlated to the conversion of one anisotropic (Jahn-Teller distorted) Mn³⁺ (S = 2) to one nearly isotropic Mn²⁺ (S = ⁵/₂).