page_title: Carborane
section_title: Dicarba clusters
hierarchical_section_title: Carborane / Preparation / Dicarba clusters
caption_attribution_description: English: structure of C2B4H8
context_page_description: Carboranes are electron-delocalized clusters composed of boron, carbon and hydrogen atoms that may also contain other metallic and nonmetallic elements in the cluster framework. Like many of the related boron hydrides, these clusters are polyhedra or fragments of polyhedra, and are similarly classified as closo-, nido-, arachno-, hypho-, etc. based on whether they represent a complete polyhedron, or a polyhedron that is missing one, two, three, or more vertices. Carboranes are a notable example of heteroboranes.
  Carboranes have as few as 5 and as many as 14 atoms in the cage framework are known, but the majority have two cage carbon atoms; of these, the best-known series is that of the closo-C₂BₙHₙ₊₂ systems where n = 3 to 12. However, carboranes having 1 to 6 cage carbon atoms have been prepared, as have a number of carborane mono- and dianions. The icosahedral CB₁₁H₁₂⁻ anion is a strong acid, and its polychlorinated derivative H is a superacid.
  The icosahedral charge-neutral closo-carboranes, 1,2-, 1,7-, and 1,12-C₂B₁₀H₁₂ are particularly stable and are commercially available.
context_section_description: Dicarbaboranes can be prepared from boron hydrides using alkynes as the source of the two carbon centers. In addition to the closo-C₂BₙHₙ₊₂ series mentioned above, several open-cage dicarbon species are known including nido-C₂B₃H₇ (isostructural and isoelectronic with B₅H₉) and arachno-C₂B₇H₁₃.
  Syntheses of icosahedral closo-dicarbadodecaborane derivatives (R₂C₂B₁₀H₁₀) employ alkynes as the R₂C₂ source and decaborane (B₁₀H₁₄) to supply the B₁₀ unit.
caption: Structure of nido-C2B4H8, highlighting some trends: carbon at the low connectivity sites, bridging hydrogen between B centers on open face.[10]
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