Two series of heterometallic FeIII-LnIII compounds, [FeIII4LnIII2([small mu ]3-OH)2(mdea)4(m-NO2C6H4COO)8][middle dot]3MeCN where Ln = Y (1) and Dy (2) and [FeIII6LnIII3([small mu ]4-O)3([small mu ]3-O)(mdea)5(m-NO2C6H4COO)9][middle dot]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 [degree]C in MeCN. The magnetic properties of all four compounds have been measured and show that compounds 2 and 4 containing DyIII ions exhibit slow relaxation of magnetization characteristic of Single Molecule Magnetic (SMM) behaviour
