Pyrolysis of trimethylborane. Part 2. Formation of carbaboranes and other boron-containing compounds

The pyrolysis of BMe3 has been studied by gas chromatography and mass spectrometry; effects of varying the pyrolysis time and temperature have been investigated. Compounds formed include BMe2Et, Me2BCH2BMe2, carbaboranes Me3B3C2H2, Me5B5C2H2, and 2,4,6,8,9,10-hexamethyl-2,4,6,8,9,10-hexabora-adamantane (Me6B6C4H4). The pyrolysis of BMe3–H2 mixtures, in marked contrast to that of pure BMe3, gives a mixture of carbaboranes of formulae MexH(5 –x)B5C2H2(x= 2–5) in high overall yield (60–66%). Pyrolyses of BMe3 in the presence of D2, C2H6, and HgMe2 provide evidence for the involvement of methyl radicals in the reaction.