Cluster Fusion: Face-Fused Macropolyhedral Tetracobaltaboranes

In an effort to isolate the 16-vertex supraicosahedral cobaltaborane [(Cp∗Co) 3 B 12 H 12 Co{Cp∗CoB 4 H 9 }] (Cp∗ = η 5 -C 5 Me 5 ), we have pyrolyzed an in situ generated intermediate, obtained from the fast metathesis of [Cp∗CoCl] 2 and [LiBH 4 ·THF], with an excess amount of [BH 3 ·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 {Co 3 B 9 }, tetrahedral {B 4 }, and 10-vertex {CoB 9 } units. The reaction also yielded a 20-vertex face-fused cluster that contains icosahedral {Co 4 B 8 }, square-pyramidal {CoB 4 }, tetrahedral {Co 2 B 2 }, and nido-{CoB 7 } units.