Nido-polyborane

Chemistry of Selected nido- and closo-Polyborane Anions I 67... 

In the early 1960s it was recognized (6,187) that there were bonding similarities between the pentagonal face of the isomeric [nirio-(y HjJ2- ions and the well-known cyclopentadienide ion (Cp ) [CydJ- (Fig. 16). The isomeric nido-C2B9H1 J2- ions, which are commonly known as dicarbollide ions, and many other carborane anions, form stable complexes with most of the metallic elements. Indeed nearly all metals can be combined with polyborane hydride clusters to produce an apparently limitless variety of cluster compounds. 

Alkyl derivatives of the nido-carborane, 2-CB5H9, are found as side products from the thermal (200°C) reaction between pentaborane (9) and acetylenes (see 5.3.2.7.3). These alkyl derivatives of 2-CB5H9 are formed from the internal 1,1 addition of two B—H bonds of the polyborane to the acetylene. 

---