“…In recent years, molecule-based magnetic materials have attracted extensive attention due to their important properties and potential application prospects. − Among them, the 3d–4f heterometallic complexes exhibit various structures and excellent magnetic properties which are significant in both crystal engineering and magnetism investigations. − Many 3d–4f complexes with finite nuclear clusters and infinite structure chains, layers, and networks have been synthesized with different strategies. ,,− In the high-nuclear clusters or coordination polymers, it is found that some 3d–4f clusters have small nuclearity as building blocks, which are connected to each other through the 4f ions. ,− However, the connections that are not conducive to transfer magnetic interactions for 4f electrons are inner shell electrons and are not coupled effectively with other spin carriers . To avoid the above problems, small 3d–4f clusters should be connected by a “magnetic bridge” through the 3d ions.…”