Rational Assembly of High‐Spin Polynuclear Magnetic Complexes into Coordination Networks: the Case of a [Mn4] Single‐Molecule Magnet Building Block

Abstract

The synthesis of transition‐metal high‐spin complexes and of infinite coordination networks of these high‐spin carriers now represents a recognized subdiscipline of coordination chemistry. This new research trend has been particularly encouraged by the discoveries that molecular and one‐dimensional coordination aggregates may behave as nanomagnets, as illustrated by the so‐called single‐molecule magnets (SMMs) and single‐chain magnets (SCMs). While the synthesis of isolated polynuclear high‐spin complexes still rely mostly on serendipitous assembly with appropriate ligands, the synthesis of SCMs or extended networks of high‐spin complexes demands a more designed and controlled bottom‐up assembly of precursor complexes and bridging species selected for their coordination abilities. In this context, the case of a [Mn 4] SMM is unique in the literature, as one‐, two‐, and three‐dimensional networks have been rationally designed by using this SMM unit as a building block, giving rise to original magnetic properties. This review gathers all reported systems that we know of, having the corresponding [Mn 4 O 6] core, either in isolated complexes or in frameworks. Their structures and, when relevant, the synthetic strategy and magnetic properties are described. The demonstrated and potential outcomes, in terms of physical properties, of such coordination assemblies of high‐spin complexes are then discussed. These are highlighted through examples with other building blocks, to broaden the scope of possible strategies and building blocks, and thus provide a basis for the further development of this promising area. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)