Synthesis of 3d metallic single-molecule magnets

The phenomenon of single-molecule magnetism was established in the early 1990s with the cluster [Mn12O12(AcO)(16)(H2O)(4)]. Since then, a large number of compounds displaying this behaviour have been synthesized. The vast majority of these consist of coordination clusters of 3d transition metals prepared by self assembly processes where the structure of the final product has not been predicted. The majority feature manganese ions, primarily in the Mn-III oxidation state, but over the years the search for novel examples of such compounds has been extended to other metals of the 3rd row, including iron, nickel, vanadium and cobalt. A host of new approaches and synthetic methodologies have been successfully explored and developed in order to prepare SMMs with new and improved properties. This review covers the synthesis and magnetic properties of SMMs consisting of homometallic coordination clusters of 3d transition metals made via serendipitous self-assembly - by far the largest source of such species - together with a brief overview of emerging methods.