Design and Self-Assembly of Ferrocene-Functional Heterometal–Oxo Clusters with the M(III)4O4 Cubane Core

In this work, we synthesized two Cu-based heterometal–oxo clusters 1 and 2 based on M(III)4O4 (M = Fe/In) cubane centers and obtained the corresponding dimers 3 and 4 by connecting Cu atoms on the cluster cores with the auxiliary ligand 4,4′- bipyridine. They were characterized by single-crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), and other tests. We conducted magnetic property study on compounds 1–4. The variable-temperature magnetic susceptibility test shows that compounds 1 and 3 exhibit significant ferromagnetic interactions at low temperatures, while compounds 2 and 4 exhibit overall antiferromagnetic interactions. When the metal at the cubane changes from magnetic Fe to nonmagnetic In, the magnetic interactions in the compound are weakened to a certain extent. Through dimerization, the extreme values of the variable-temperature magnetic susceptibility appear (1 to 3)/disappear (2 to 4) in the low-temperature section. We investigated the magnetic structure correlation of compounds 1–4 through bond lengths, bond angles, and distances between magnetic atoms. The results showed that compounds 1–4 exhibited significant magnetic coupling diversity.