Robotic Stepwise Synthesis of Hetero-Multinuclear Metal Oxo Clusters As Single-Molecule Magnets

An efficient stepwise synthesis method for discovering new heteromultinuclear metal clusters using a robotic workflow is developed where numerous reaction conditions for constructing heteromultinuclear metal oxo clusters in polyoxometalates (POMs) were explored using a custom-built automated platform. As a result, new nonanuclear tetrametallic oxo clusters {FeMn}LuA in TBA[(A-α-SiWO)FeMnO{Lu(acac)}A] (; A = Ag, Na, K; TBA = tetra--butylammonium; acac = acetylacetonate) were discovered by the installation of diamagnetic metal cations A into a paramagnetic {FeMn}Lu unit in TBA[(A-α-SiWO)FeMnO{Lu(acac)}] (). POMs exhibited single-molecule magnet properties with the higher energy barriers for magnetization reversal (, 40.0 K; , 40.3 K; , 26.7 K) compared with that of the parent (19.7 K). Importantly, these clusters with unique properties were constructed as designed by a step of the predictable sequential multistep reactions with the time-efficient platform.