Cluster Fusion: Face-Fused Macropolyhedral Tetracobaltaboranes

In an effort to isolate the 16-vertex supraicosahedral cobaltaborane [(Cp*Co)(3)B12H12Co-{Cp*CoB4H9}] (Cp* = eta(5)-C5Me5), we have pyrolyzed an in situ generated intermediate, obtained from the fast metathesis of [Cp*CoCl](2) and [LiBH4 center dot THF], with an excess amount of [BH3 center dot THF]. Although the objective of isolating the 16-vertex cobalt analogue was not achieved, the reaction yielded a closo-19-vertex face-fused cluster presenting icosahedral {Co3B9}, tetrahedral {B-4}, and 10-vertex {CoB9} units. The reaction also yielded a 20-vertex face-fused cluster that contains icosahedral {Co4B8}, square-pyramidal {CoB4}, tetrahedral {Co2B2}, and nido-{CoB7} units.