Accidentally on purpose: construction of a ferromagnetic, oxime-based [MnIII2] dimer

Abstract

The serendipitous self-assembly of the complex [Mn^III₂Zn^II₂(Ph-sao)₂(Ph-saoH)₄(hmp)₂] (1),whose magnetic core consists solely of two symmetry equivalent Mn(III) ions linked by two symmetry equivalent –N–O– moieties, provides a relatively simple model complex with which to study the magneto-structural relationship in oxime-bridged Mn(III) cluster compounds. Dc magnetic susceptibility measurements reveal ferromagnetic (J = +2.2 cm⁻¹) exchange resulting in an S = 4 ground state. Magnetisation measurements performed at low temperatures and high fields reveal the presence of significant anisotropy, with ac measurements confirming slow relaxation of the magnetisation and Single-Molecule Magnetism behaviour. Simulations of high field, high frequency EPR data reveal a single ion anisotropy, D_(Mn^III) = −3.83 cm⁻¹. DFT studies on a simplified model complex of 1 reveal a pronounced dependence of the exchange coupling on the relative twisting of the oxime moiety with respect to the metal ion positions, as suggested previously in more complicated [Mn^III₃] and [Mn^III₆] clusters.