Cluster Fusion: Face-Fused Macropolyhedral Tetracobaltaboranes.

In an effort to isolate the 16-vertex supraicosahedral cobaltaborane [(Cp*Co)3B12H12Co{Cp*CoB4H9}] (Cp* = η5-C5Me5), we have pyrolyzed an in situ generated intermediate, obtained from the fast metathesis of [Cp*CoCl]2 and [LiBH4·THF], with an excess amount of [BH3·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 {B4}, 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.