Heteroborane
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-," etc. based on whether they represent a complete ("closo-") polyhedron, or a polyhedron that is missing one ("nido-"), two ("arachno-"), or more vertices. Heteroboranes can be classified by converting the heteroatom to a BH group that has the same number of electrons.