Carborane chemistry supraicosahedral

It is anticipated that the area of supraicosahedral carborane chemistry will expand rapidly since the materials like ort o-carborane needed to make these 13- and 14-vertex carboranes are commercially available. 

Structurally, metallacarborane chemistry is the most fully documented area of carborane chemistry. There is not enough space here for a comprehensive survey, but Tables 3.2 and 3.3 and Figure 3.22 show the formulae and skeletal structures of some representative examples. More comprehensive compilations of structural data are to be found in References 1-3 and 199. Metals have been incorporated into the whole range of known carborane deltahedra, and indeed their presence has allowed supraicosahedral systems to be made that are without precedent among metal-free carboranes or boranes, as outlined below. 

A breakthrough in 2003 into supraicosahedral carborane chemistry (as distinct from supraicosahedral metallacarborane chemistry) came from the use of external tethers to hold together the two cage carbon atoms during syntheses. - - Hie groups of A. J. Welch - - - and Z. have... 

Now that access into supraicosahedral carborane chemistry has been achieved, it appears likely that more higher carboranes will be prepared, and that further ingenious synthetic routes to such systems will be found. Though the stabilities of the products may not rival those of icosahedral carboranes, it will be interesting to see whether many of the higher carboranes or boranes envisaged by Lipscomb,--- Hoffmann,Schleyer,34,35,55,22 230... 

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