A Cationic Metal Glue Strategy for Expanding Paramagnetic Hetero-Multinuclear Metal-Oxo Clusters within Polyoxometalate Ligands

Precise structural design of large hetero-multinuclear metal-oxo clusters is crucial for controlling their large spin ground states and multielectron redox properties for application as a single-molecule magnet (SMM), molecular magnetic refrigeration, and efficient redox catalyst. However, it is difficult to synthesize large hetero-multinuclear metal oxo clusters as designed because the final structures are unpredictable when employing conventional one-step condensation reaction of metal cations and ligands. Herein, we report a cationic metal glue strategy for increasing the size and nuclearity of hetero-multinuclear metal-oxo clusters by using lacunary-type anionic molecular metal oxides (polyoxometalates, POMs) as rigid multidentate ligands. The employed method enabled the synthesis of {(FeMn4)Mn2Ln2(FeMn4)} oxo clusters (Ln=Gd, Tb, Dy, and Lu), which are the largest among previously reported paramagnetic hetero-multinuclear metal-oxo clusters in POMs and showed unique SMM properties. These clusters were synthesized by conjugating {FeMn4} oxo clusters with Mn and Ln cations as glues in a predictable way, indicating that the cationic metal glue strategy would be a powerful tool to construct desired large hetero-multinuclear metal clusters precisely and effectively. A cationic metal glue strategy for increasing the size and nuclearity of hetero-multinuclear metal-oxo clusters is demonstrated by using lacunary-type polyoxometalates (POMs) as rigid multidentate ligands. The method enabled the expansion of {FeMn4} to {(FeMn4)Mn2Ln2(FeMn4)} oxo clusters (Ln=Gd, Tb, Dy, and Lu), which are the largest among previously reported paramagnetic hetero-multinuclear metal-oxo clusters in POMs.image

Automated summary

A cationic metal glue strategy utilizing lacunary-type polyoxometalates (POMs) as rigid multidentate ligands is demonstrated for increasing the size and nuclearity of hetero-multinuclear metal-oxo clusters. The method enabled the synthesis of {(FeMn4)Mn2Ln2(FeMn4)} oxo clusters (Ln=Gd, Tb, Dy, and Lu), which are currently the largest reported paramagnetic hetero-multinuclear metal-oxo clusters in POMs.