Synthesis, Structure, and Reactivity of 1,2-(1',1',2',2'-Tetramethyldisilane-1',2')carborane.

The novel strained compound 1,2-(1',1',2',2'-tetramethyldisilane-1',2')carborane (1) was synthesized by the reaction of 1,2-dilithiocarborane and dichlorotetramethyldisilane. Compound 1 was characterized by solution methods and its structure determined by single-crystal X-ray diffraction. In contrast to its organic analogue o-(disilanyl)phenylene, the reaction of 1 with ethanol leads to cleavage of a Si-C bond rather than a Si-Si bond. Similarly to other cyclic disilanes, exposure of a solution of 1 to oxygen leads to the insertion of an oxygen atom into the Si-Si bond. The structure of the oxygen inserted product was also determined by X-ray crystallography. The general chemistry and attempts at polymerizing 1 are briefly discussed.

Electrochemical Properties of Bis(dicarbollide)uranium Dibromide.

The cyclic voltammogram of [(eta(5)-C(2)B(9)H(11))(2)UBr(2)].2[Li(THF(4))] shows the electrochemical generation of a uranium(III) species. Subsequent Na/Hg reduction of [(eta(5)-C(2)B(9)H(11))(2)UBr(2)].2[Li(THF(4))] leads to the new isolable uranium(III) species [(eta(5)-C(2)B(9)H(11))(2)UBr(THF)].2[Li(THF)(x)()] (x = 2-4). The green uranium(III) complex was characterized by NMR and elemental analysis and its structure determined by single-crystal X-ray crystallography. The coordination geometry around the dinegative uranium(III) moiety is pseudotetrahedral with two dicarbollide ligands, a bromide ligand, and a THF ligand. The electrochemical properties of the dicarbollide complex are discussed and compared to similar cyclopentadienyluranium complexes.