Butterfly-like Heteronuclear 3d-4f Metal Clusters: Synthesis, Structures, Magnetic Properties, and Magnetocaloric Effect

This study describes the self-assembled synthesis, characterization, and structural features of two new heterometallic Fe(6)Ln clusters, [Fe(6)Ln(mu(3)-OH)(2)(mdea)(6)(N-3)(6)(NO3)] (Ln = Y (1), Gd (2); mdeaH(2) = N-methyldiethanolamine). The obtained compounds possess a unique crystalline structure with a vertex-sharing butterfly-like Fe(3)LnFe(3) motif and a rare type of 2,3,4M7-1 topology. The compounds show a new prototype structure with a distinctive arrangement of a lanthanide center between the Fe-3 triangles. Magnetic properties of the obtained clusters were investigated in detail. In 1, the best fit through a spin Hamiltonian to the experimental data of both magnetic susceptibility and magnetization curves gave J values ranging from -5.5 to -11.1 cm(-1). In 2, these values vary from -18.0 to -31.5 cm(-1). The cluster 2 also showed a magnetocaloric effect (MCE) with a -Delta S-m value of 10.6 J kg(-1) K-1 (16.3 J mol(-1) K-1) at 2.0 K. This effect is superior to that of other metallacrown compounds (with one Gd inside of an antiferromagnetic matrix of iron centers). The obtained compounds bring a new example of heptametallic clusters into a family of heteronuclear iron(III)-lanthanide derivatives with notable structural characteristics and magnetic behavior.

Automated summary

This study describes the synthesis of two new heterometallic Fe(6)Ln clusters and investigates their unique crystal structure and magnetic properties.