Collect. Czech. Chem. Commun. 1999, 64, 971-976

Oxidation of the [nido-6,9-C2B8H10]2- Anion - An Alternative Source of the 1,6- and 1,10-Dicarba-closo-decaboranes(10)

Bohumil Štíbra,*, Zbyněk Janoušeka, Matthew Trammellb, Bohumír Grünera and Zbyněk Plzáka

a Institute of Inorganic Chemistry, Academy of Sciences of the Czech Republic, 250 68 Řež near Prague, Czech Republic
b University of Colorado, Colorado, Campus Box 215, Boulder, CO 80 309-215, U.S.A.


The oxidation of the [nido-6,9-C2B8H10]2- (1) dianion with CuCl2, is supposed to proceed via an unstable closo-2,6-C2B8H10 (2) intermediate, which is then rearranged into closo-1,6-C2B8H10 (3) (yields 30-35%). The synthesis is accompanied by the formation of the isomeric closo-dicarbaboranes 1,10-C2B8H10 (4) and 1,2-C2B8H10 (5) and the whole procedure can be modified to isolate only isomer 4 (yield 35%). Side products from the synthesis consist of a complex and so far unseparable mixture, in which arachno-4,6-C2B7H13, chloro derivatives closo-C2B8H9Cl, and trimeric compounds of a closo-(C2B8H9)2-C2B8H8 formulation were detected by GLC/MS techniques. These findings point to the involvement of a radical-chain mechanism in the reaction.

Keywords: Boranes; Carboranes; Dicarbaboranes; Ten-vertex closo-dicarbaboranes; Radical oxidations; Copper (II) chloride.