Oxidation of the [nido-6,9-C2B8H10](2-) anion - An alternative source of the 1,6-and 1,10-dicarba-closo-decaboranes(10)

The oxidation of the [nido-6,9-C2B8H10](2-) (1) dianion with CuCl2, is supp osed to proceed via an unstable closo-2,6-C2B8H10 (2) intermediate, which i s 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 arrrchno-4,6-C2B7H13 , chloro derivatives closa-C2B8H9Cl, and trimeric compounds of a closo-(C2B 8H9)(2)-C2B8H8 formulation were detected by GLC/MS techniques. These findin gs point to the involvement of a radical-chain mechanism in the reaction.