A single molecule magnet to single molecule magnet transformation via a solvothermal process: Fe4Dy2 → Fe6Dy3.

Two series of heterometallic Fe(III)-Ln(III) compounds, [FeLn(μ3-OH)2(mdea)4(m-NO2C6H4COO)8]·3MeCN where Ln = Y (1) and Dy (2) and [FeLn(μ4-O)3(μ3-O)(mdea)5(m-NO2C6H4COO)9]·3MeCN where Ln = Y (3) and Dy (4), were synthesized. Compounds 1 and 2 were obtained under ambient conditions, whereas 3 and 4 were obtained via a solvothermal transformation process by heating 1 or 2 at 120 °C in MeCN. The magnetic properties of all four compounds have been measured and show that compounds 2 and 4 containing Dy(III) ions exhibit slow relaxation of magnetization characteristic of Single Molecule Magnetic (SMM) behaviour.