Synthesis and structural studies of subicosahedral adjacent-carbon carboranes

Synthesis and structural investigations using combined NMR, X-ray crystallographic and ab initio/IGLO/NMR techniques, were performed on a variety of new subicosahedral carboranes with adjacent cage carbons. Acetonitrile-induced cage degradation of arachno-4,5-C2B7H12- produced nido-4,5-C2B6H9- in nearly quantitative yield, which can then be protonated to produce the neutral carborane nido-4,5-C2B6H10 in good yield. Both of these nido electron-count clusters have an arachno-type geometry.