Syntheses of C-substituted icosahedral dicarbaboranes bearing the 8-dioxane-cobalt bisdicarbollide moiety

The treatment of 1,2-, 1,7- and 1,12-carbaborane lithiated isomers with [3,3′-Co-8-(CH2CH2O)2-(1,2-C2B9H10)-(1′,2′-C2B9H11)] (1) at molar ratios 1:1 or 1:2 at room temperature in THF leads generally to the formation of a series of orange double-cluster mono and dianions. These were characterized by NMR and MS methods as [1′′-X-1′′,2′′-closo-C2B10H11]−, [2]−; [1′′-X-1′′,7′′-closo-C2B10H11]−, [3]− and [1′′-X-1′′,12′′-closo-C2B10H11], [4]− for the monoanions, whereas [1′′,2′′-X2-1′′,2′′-closo-C2B10H10]2−, [2]2−; [1′′,7′′-X2-1′′,7′′-closo-C2B10H10]2−, [3]2−; and [1′′,12′′-X2-1′′,12′′-closo-C2B10H10]2−, [4]2− for the dianions (where X = 3,3′-Co-8-(CH2CH2O)2-(1,2-C2B9H10)-1′,2′-(C2B9H11)). Moreover, these borane-cage subunits can be easily modified via attaching variable substituents onto cage carbon and boron vertices, which makes these compounds structurally flexible potential candidates for BNCT of cancer and HIV-PR inhibition.