Linked and Mercury-Bridged Nido-Carboranes. High-Yield Synthesis of mu, mu' - ((CH3)2C2B4H5)2Hg, Conversion to 5,5'-((CH3)2C2B4H5)2, Cleavage, and Oxidative Addition of Benzene. Synthesis of mu, mu'-(B5H8)2Hg.
VIRGINIA UNIV CHARLOTTESVILLE DEPT OF CHEMISTRY
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The nido-carborane anion 2,3-CH32C2B4H5- reacts readily with anhydrous HgCl2 in THF at room temperature, producing the biscarboranyl mercuryII complex mu,mu-CH32C2B4H52Hg in which the metal is bound to two carborane ligands via B-Hg-B three-center, two-electron bridge bonds. On heating at 180 deg. in benzene, this compound quantitatively expels free mercury and forms the B-B linked nido-carborane 5,5-CH32C2B4H52 as a single pure isomer. Air oxidation of the linked carborane in benzene solution results in cleavage of the carborane-carborane B-B bond and oxidative addition of benzene to give 4-C6H5-2,3-CH32C2B4H5, an apparently air-stable derivative of nido-2,3-C2B4H8. Similar treatment of the linked carborane in C6D6 gives the corresponding hexadeuterated carborane product. The reaction of B5H8 - ion with HgCl2 in THF produces mu,mu-B5H82Hg, a stable solid in which mercury is evidently bridge-bonded to two pentaborane ligands. Author
- Organic Chemistry