C-Carbaboranes

C -Carbaboranes.- A MesSi-group is removed from nido 

2-(Me3Si)C2B4H7 (4) quantitatively.20 The structure of (4) was determined by electron diffraction. 

Reaction of Et3NBH3 with nido-2.3-Et2C2B4He at 140 C afforded closo-2,3-Et2C2B5Hs which underwent isomerisation at 320°C to 2.4-Et2C2B5Hs.21 

Rearrangement of 5-Me-6-Cl-2.4-C2B5H5 to a mixture of all eight possible B-substituted isomers was studied at 295°C.22 Rates and the sequence of rearrangements were noted and shown to be consistent with a DSD-mechanlsm. The relative stabilities of the isomers were discussed. 

Electrophilic (D.C1,Br,I.SH) and nucleophilic (Bu) substitution of arachno 4,6-C2B7Hi3 gave 3- or 5-derivatlves and 

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