Magnetic materials based on heterometallic CrII/III–LnIII complexes

Abstract

Accommodating disparate spin centres within a single ensemble is a valuable synthetic strategy to obtain interesting molecular magnetic materials. 3d–4f heterometallic complexes are one such subclass that has been extensively explored for the last three decades owing to their interesting magnetic properties. The primary reason is that the bridging ligand mediates magnetic super-exchange between 3d and 4f ions to considerably reduce the prevalent quantum tunnelling of magnetisation (QTM) in such complexes. Among the 3d–4f family, Cr^III–Ln^III assemblies nicely demonstrate the pivotal role played by strong exchange interactions between these two individual spin carriers to engender interesting single-molecule magnet (SMM) properties. In fact, this part of heterometallic chemistry has flourished greatly in the last decade despite its late development. In this review we provide an extensive synthetic, structural, magnetic, and magnetocaloric description of various Cr^III–Ln^III complexes along with their fundamental mechanisms of exchange interaction. Finally, we provide some possible solutions to improve the SMM properties of the Cr^III–Ln^III and other heterometallic complexes.