Symmetry-breaking substitutions of [Re(CN)₈]^3- into the centered, face-capped octahedral clusters (CH₃OH) ₂₄M₉M′₆(CN)₄₈ (M = Mn, Co; M′ = Mo, W)

The diamagnetic complex [Re(CN)₈]^3- is shown to react with Mn²⁺ ions in methanol to generate the centered, face-capped octahedral cluster (CH₃OH)₂₄Mn₉Re ₆(CN)₄₈, which is structurally analogous to (CH ₃OH)₂₄Mn₉Mo₆(CN)₄₈. Related reactions involving stoichiometric mixtures of octacyanometalate complexes generate the substituted species (CH₃OH) ₂₄Mn₉Mo₅Re(CN)₄₈, (CH ₃OH)₂₄Co₉Mo₅Re(CN)₄₈, (CH₃OH)₂₄Mn₉Mo₃Re ₃(CN)₄₈, (CH₃OH)₂₄Mn ₉W₅Re(CN)₄₈ and (CH₃OH) ₂₄Co₉W₅Re(CN)₄₈, in which the O _h symmetry of the cluster core is broken. Reassessment of the magnetic properties of the Mn₉Mo₆(CN)₄₈ cluster confirm that it possesses a ground state spin of S = 39/2, but does not exhibit single-molecule-magnet behavior. Lowering the symmetry of the molecule by substitutions of Re^V at one or three of the Mo^V sites does not lead to an overall increase in the magnetic anisotropy, as probed by ac magnetic susceptibility measurements. A similar result occurs for the other substituted species, with the important exception of the new single-molecule magnet (CH₃OH)₂₄Co₉W₅Re(CN) ₄₈, for which the spin reversal barrier is significantly reduced relative to that observed previously in (CH₃OH)₂₄Co ₉W₆(CN)₄₈.