A new family of hetero-tri-metallic complexes [M(CuTb)]n (n = 1, 2, ∞; M = Co, Cr, Fe): synthesis, structure and tailored single-molecule magnet behavior

Abstract

A new family of hetero-tri-metallic complexes [M(CuTb)]_n (M^III = Co, Cr, Fe; n = 1, 2, ∞), composed of three series of three compounds (oligo- and poly-nuclear complexes based on [Cu–Tb] subunits), is presented and fully characterized. These nine compounds, viewed as different assemblies of single-molecule magnet (SMM) building blocks, connected to various hexacyanometalate centers, illustrate how the SMM behavior of the [CuTb] moiety can be modulated via the control of intermolecular interactions. Specifically, the combination of the “non-innocent” diamagnetic [Co^III(CN)₆]³⁻ center with a [Cu–Tb]³⁺ moiety enabled isolation of the magnetic entities, resulting in an improvement of the SMM behavior (ranging from U_eff = 5–7 cm⁻¹ to 15–17 cm⁻¹).