text: Even greater in scope than metalloboranes are metallacarboranes.  These cages have carbon vertices, often CH, in addition to BH and M vertices. A well-developed class of metallacarboranes are prepared from dicarbollides, anions of the formula [CBH].  These anions function as ligands for a variety of metals, often forming sandwich complexes. 
  Some metalloboranes are derived by the metalation of neutral carboranes. Illustrative are the six-and seven-vertex cages prepared from closo-.  Reaction of this carborane with iron carbonyl sources gives closo Fe- and Fe2-containing products, according to these idealized equations:
  A further example of insertion into a closo carborane is the synthesis of the yellow-orange solid closo-1,2,3-:
  A closely related reaction involves the capping of an anionic nido carborane 
  The last reaction is worked up with acid and air.