Small cobaltacarborane clusters in synthesis. Peralkylation, perhalogenation, and macrocycle construction

Methods are described for achieving stepwise replacement of all BH terminal hydrogens in CoC2B4 clusters with halogen or alkyl groups, leading to complexes such as Cp*Co(2,3-Et2C2B4X4) (X=Me or I) and Cp*Co(2,3-Et2C2B4IMe2[O3SCF3]). Building on earlier work on B-functionalization of small metallacarboranes via metal-catalyzed cross-coupling, two- and three-dimensional macrocycles containing four to six metal centers have been constructed systematically from monomeric precursor complexes.