Oxidation of germa- and stanna-closo-dodecaborate.

The oxidation of closo-heteroborates [GeB11H11](2-) and [SnB11H11](2-) is presented. Upon oxidation germa-closo-dodecaborate yields a symmetrical dimer exhibiting a Ge-Ge bond between two clusters. This dimer shows sulphur insertion into the Ge-Ge bond at room temperature. In contrast, oxidation of the homologous tin cluster results in an unsymmetrical dimer bearing an Sn-B bond between two clusters. The Sn-B dimer is also the product of the hydride abstraction reaction. In the presence of the donor ligand 2,2'-bipyridine, the oxidation of closo-cluster [SnB11H11](2-) leads to the Sn(IV)-half sandwich coordination compound [bipy-SnB11H11] which dissolves in DMSO to give the Sn(IV)-adduct [bipy(DMSO)-SnB11H11].