Monocarboranes are clusters with  cages. The 12-vertex derivative is best studied, but several are known.
Typically they are prepared by the addition of one-carbon reagents to boron hydride clusters. One-carbon reagents include cyanide, isocyanides, and formaldehyde. For example, monocarbadodecaborate () is produced from decaborane and formaldehyde, followed by addition of borane dimethylsulfide.
Monocarboranes are precursors to weakly coordinating anions.