Carbaborane Synthesis, Characterisation and Reactions

Ca-Carbaboranes.- A new route to nido-4,5,7,8-Me2Et2C4B4H4 uses metal promoted (NaH/NlCl2) insertion of but-2-yne into 

The former is dimeric and contains a layer of four Ll atoms 

Possibly some of the most Interestlnp work in synthesis presently concerns carbon rich -carbaboranes. Three isomers of compounds have now been reported. The parent compound and 

Previously only adamantane type derivatives of C.B -systems had 4.. 4 13b 

The formation of nido CriegSi)2C BgHjQ was achieved by elimination of Me SiH molecules 

This section on C -compounds cannot be concluded without reference to recent experimental and theoretical studies of borlreneCR3C2B) 1,3-diborete (R., C.,B,R., 3. and 

3-diboretane (R C2B2R2 derivatives, since related species clearly play important roles in the chemistry of carbaboranes 

The preparation of the first 1,3-diboraallyl system with a B-H-B bridge Is noteworthy in the light of the above 

Attempts have failed to reproduce the reported syntheses of hexaaalky1-1,4-d1bora-2,5-cyclohexadlenes1from R2C2 and the Intermediate MeB . Instead, nldo-2,3,4,5 - tetracarbaboranes (R4C4B2R 2) hd various organoboron bromides were the major products.  

Direct reaction of B5H9 with Me3SlC CR (R = MesSl.He.H) gave high yields of air-stable 2-(Me3Si)-3-R-2.3-C2B4H6 products. 4 

All possible B-substltuted mono- and dl- bromo- and iodo-derlvatlves of 2.4-C2B5H7 have been synthesised except 1,7-Br2-2,4-C2B5H5.Kinetic data for the rearrangements of 5-X-2,4-C2B5H6 and 5.6-X2-2,3-C2 B5H5 isomers (X = Cl. b bj. jlSa) have been obtained. These studies lead to Isomer stability sequences for example In the mono-derivatives, 3- 5- 1-X for Cil5b or BrISa but 5- 3- 1-X for Possible mechanisms for 

B-fluoro-der1vatives of 2,4 C2B5H7 were produced when [R4N]F was reacted with 5-Br - 2,4-C2 B5 He or 3,5--12-2.4-C2 B5 H5.1 A more 

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This Chaptsr concerns the synthesis, characterisation, reactions, and properties of carbaboranes and their a- and cape-bonded metal derivatives. 

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