Metal-Metal Cooperative C─F and S─F Bond Cleavage by Low-Valent Tetracobalt Clusters and Water-Assisted Fluoroarene Hydrodefluorination.

We report the self-assembly of paramagnetic, tetrahedral tetra-cobalt(I) clusters supported by structurally flexible N-donor, bipyridine-based ligand platforms, which are capable of structural rearrangement of their tetrametallic core via small molecule activation. In particular, CoI 4 clusters cleave S─F and C─F bonds in SF6 and fluoroarenes in the presence of water, resulting in fluoride trapping between two Co atoms in an overall tetrametallic CoII core, while aerobic oxidation of a tetra-cobalt(I) cluster results in isolation of a CoIII oxo-bridged cubane cluster. Hydrodefluorination of polyfluorinated arenes was achieved using water without the need to utilize silanes or boranes: isotope-labeling experiments confirmed that the hydrogen in the hydrodefluorinated products originates from water.