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.