Nido- and Hypho-lithiacarboranes

Besides the tetrameric aggregates with lithium ions, a polymeric meander-like 

On the other hand, the mono-, bis- and trishomoaromatic (N, O, P) species are formally derived from the triborirane dianion M by successive incorporation of methylene bridges into the ring. 

Insertion of a third methylene bridge into M leads to hypho P with 20 SE. The tetrameric species [Li(thp)2Li87]4 and Li([12]cr-4)2 4(Li87)4 suggest that one Li+ has to be assigned to each [(MeCH)3BMe]32 arachno cluster. The former is coordinated by two C-B bonds of the neighboring cluster [103]. This increases the total 

a dashed circle (7r,cr-distorted, N and O) or a dashed triangle (essentially a, P). 

Carboranes containing one, two or more carbon and up to six boron atoms have been shown to be much more stable with organyl groups than with hydrogen substituents. In particular B-ethyl groups stabilize carboranes kinetically with re- 

---