Heteroboranes are classes of boranes, at least one boron atom is replaced by another element. Like many of the related boranes, these clusters are polyhedra and are similarly classified as closo-, nido-, arachno-, hypho-, according to the so-called electron count. Closo- represents a complete polyhedron, while nido-, arachno- and hypho- stand for polyhedrons that are missing one, two and three vertices.