Inelastic Neutron Scattering Study of Electron Reduction in Mn12 Derivatives

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).