A [Mn18Dy] SMM resulting from the targeted replacement of the central MnII in the S=83/2 [Mn19]-aggregate with DyIII

Anisotropy can be introduced into the [Mn-19]-aggregate, which currently has the highest known spin ground state of S = 83/2, by the targeted replacement of the central Mn-II cation with Dy-III leading to a [Mn18Dy] complex with the same core topology showing slow relaxation of the magnetisation.