The utilization of dianionic heavy group 14 cyclopentadienides (silole, germole, stannole and plumbole ) enabled potential for novel structural motifs and unique chemical bonding as they are even stronger donors than monoanionic Cp derivatives. However, at the same time, the coordination chemistry of these non-stabilized dianionic ligands poses a great synthetic challenge because of their intrinsically high reactivity and sensitivity, that has not yet been solved for dysprosium complexes. Compared to the parent Cp-type ligand, such dianions exhibit more versatile reactivity and coordination modes due to the additional lone pair at the heteroatom. This type of ligands has only been recently introduced into the coordination sphere of rare-earth metals (Fig. ). In 2021, Tan isolated for the first time a series of yttrium germole complexes. As for the homoleptic yttrium complex I, in addition to the η 5coordination by two germoles, each Y metal is additionally coordinated to a neighboring germole via its η 1 -mode, thus resulting a dimeric structure in the solid state. Similar dimeric structures were obtained by some of us in 2022 for the heteroleptic lanthanum sandwich compound (II) with silole and cyclooctatetraenide (COT). When using the germole instead, a one-dimensional coordination polymer (III) was isolated, which still exhibits the La-Ge intermolecular interactions. Apparently, due to the lone pair of electrons, the Lewis-basic silole and germole are acting as -donating ligands for the rare-earth metals as well, preventing their action as solely axial ligands (-donor) without the extra η 1 -coordination (-donor). This has made it particularly difficult to obtain a high-performance Dy SMM with such heterocycles.