Dicarba-closo-pentaboranes

But the discovery of the carboranes in the early 1960s revealed that bonding possibilities other than simple o-- or 7r-bonds between B and C centers were necessary to understand the structure of such compounds as 1,5-dicarba-closo-pentaborane(5) [6 in Eq. (1)], which is obtained in low yield in an electrical discharge.6 Ordinary valence conventions cannot account for the bonding of boron to five other atoms, and hence the concept of electron-deficient bonding must be invoked for boron. Although carbon seems to adhere to normal tetravalence, again it should be remembered... 

Reduction of the pentaalkyl-1,5-dicarba-closo-pentaboranes(5) 44 with elemental K opens the cluster and subsequent reaction with I2 enforces oxidative fusion of two C2B3 units to give a C4B6 cage (Scheme 3.2-36). The peralkylated hexaboraadamantane derivatives 70 (R = Me, Et X-ray structure analysis for R = Me [89]) rearrange irreversibly into the carboranes 71 with a wido-C4B6 framework [89] (X-ray structural analysis for R = Et [90]). The structure of the nido-C Bf, cluster is fluxional in solution [91]. 

PORONCOMPOUNDS - BORON HYDRIDES, HETEROBORANES AND THEIR METALLADERIVATIVES] (Vol 4) Dicarba-closo-pentaborane(5)... 

C2H5B3, 1,5-Dicarba-closo-pentaborane(5) (gas-ed), 39B, 888 C2H5BflCl, 2-Chloro-1,6-dicarbahexaborane(6) (gas-mw), 37B, 696 C2HgBF, Dimethylboron fluoride (gas-ed), 9, 337... 

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