Novel 11-Vertex, 11-Skeletal Electron Pair Tantalaborane of Unusual Shape

This work reports the synthesis and structural characterization of a hydrogen-rich tantalaborane cluster, [(Cp*Ta)(Cp*TaCl)B9H16] (2, Cp* = η5-C5Me5), obtained from the thermolysis of [BH3·thf] and an in situ generated intermediate, produced from the reaction of [Cp*TaCl4], 1, and [LiBH4·thf]. Cluster 2 has an 11-vertex nido-cage geometry. The core geometry of 2 can be derived from an icosahedron by removing the apical five-coordinate vertex. The title cluster is a rare example of an electronically unsaturated metallaborane containing four TaHB and three BHB bonds.