A High-Symmetry Double-Shell Gd30Co12 Cluster Exhibiting a Large Magnetocaloric Effect.

A high-nuclearity 3d-4f cluster of [Gd30CoII6CoIII6(OH)56(NO3)12(CH3COO)30(H2O)30]·(NO3)22·(en)3·(H2O)3 (1) was synthesized through the reaction of Gd(NO3)3·6H2O, Co(NO3)2·6H2O, and sodium acetate in a mixture of ethanediamine (en), ethanol, and deionized water. The cluster core in 1 features a double-shell structure with a Co12 icosahedron encapsulating a Gd30 icosidodecahedron. A magnetic study reveals that separating Co2+ ions with Gd3+ ions can effectively reduce the magnetic interaction of 3d-4f clusters. Significantly, the magnetocaloric effect (MCE) of 1 at 2 K and 7 T is up to 44.7 J kg-1 K-1, the largest MCE reported to date in the 3d-4f metal clusters.