Polyhedral carbathiaborane chemistry. Ten-vertex nido and arachno, eleven-vertex nido, and eight-vertex hypho families of carbathiaboranes

Abstract

Treatment of arachno-4-CB₈H₁₄ with sulfur and triethylamine in chloroform has produced the new tenvertex carbathiaborane arachno-6,9-CSB₈H₁₂, which has been used for the preparation of a series of further carbathiaborane compounds. Deprotonation with sodium hydride or 1,8-bis(dimethylamino)-naphthalene generates the [arachno-6,9-CSB₈H₁₁]^– anion. Thermolysis of the sodium salt of this anion, followed by acidification, results in comproportionation to give nido-7,9-CSB₉H₁₁ and arachno-4,6-CSB₇H₁₁. Alternatively, oxidation by acetone yields the [nido-6,9-CSB₈H₉]^– anion. Degradation of this latter anion with concentrated hydrochloric acid leads to arachno-4,6-CSB₇H₁₁. Deprotonation of this neutral carbathiaborane with sodium hydride in ether, followed by degradation by aqueous acetone of the [arachno-4,6-CSB₇H₁₀]^– anion generated in situ, gives the [hypho-7,8-CSB₆H₁₁]^– anion. This has been methylated by methyl iodide to afford neutral 8-Me-hypho-7,8-CSB₆H₁₁. The unambiguous cluster constitutions of all compounds isolated have been established by ¹H and ¹¹B NMR spectroscopy and mass spectrometry.