Studies on 2,3-dicarbahexaborane(8) and related compounds

Article abstract of DOI:10.1021/ic50022a006

The reaction between alkynes and pentaborane at elevated temperatures was studied. Increasing the number of alkyl groups about the triple bond of the alkyne enhanced the reactivity toward pentaborane and resulted in increased yields of the corresponding 2,3-dicarbahexaborane(8). Attempts to effect a direct conversion of alkynes and pentaborane to the appropriate 2,4-dicarbaclovoheptaborane(7) were unsuccessful. The decomposition of 2,3-dicarbahexaborane(8) in a silent electric discharge apparatus has given improved yields of 1,5-dicarbaclovopentaborane(5) and 1,2-dicarbaclovohexaborane(6). Earlier findings are rationalized in terms of the thermal stabilities of the latter two compounds. (1) Nomenclature adopted for C₂B₄H₈ which, previously, was called dihydrocarborane ²: R. Adams, Inorg. Chem., 2, 1087 (1963). Other adopted names for compounds mentioned in this article are: C₂B₃H₅, 1,5-dicarbaclovopentaborane(5); sym-C₂B₄H₆, 1,6-dicarbaclovohexaborane(6) unsym-C₂B₄H₆, 1,2-dicarbaclovohexaborane(6); C₂B₅H₇, 2,4-dicarbaclovoheptaborane(7). At times it will be convenient to use the term carborane in a generic sense covering the above clovo carbon-boron hydrides with skeletal carbon atoms.