closo‐[B₂₁H₁₈]⁻: A Face‐Fused Diicosahedral Borate Ion

Siamese borates: Syntheses are described for salts of the closo-[B21H18]− and fac-[B20H18]2− ions. The [B21H18]− ion is the first example of a singly charged closo-borate ion in which two icosahedral fragments are fused together such that they have a common face. The synthesis of novel weakly coordinating anions based on these frameworks is thus within reach. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2007/z604077_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.