Coordination Chemistry of Carborane Clusters: Metal-Boron Bonds in Carborane, Carboranyl, and Carboryne Complexes

Metalated three-dimensional icosahedral boron clusters often exhibit high chemical and thermal stability relative to their simple borane counterparts thus making them a convenient object to study the chemistry of metal-boron bonds. The presence of multiple reactive boron vertices makes carboranes unique ligands with unusual steric and electronic requirements. This article summarizes recent developments in coordination chemistry of neutral {C2B10} carborane clusters with a focus on metal-boron interactions. Several bonding modes are discussed, including neutral borane coordination through bridging B-H M interactions, boryl complexes with B -M bonds, multimetallic assemblies, and the BB-carboryne complex containing a three-membered (BB)>Ru metallacycle.