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

Abstract

The treatment of 1,2-, 1,7- and 1,12-carbaborane lithiated isomers with [3,3′-Co-8-(CH 2CH 2O) 2-(1,2-C 2B 9H 10)-(1′,2′-C 2B 9H 11)] ( 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-C 2B 10H 11] −, [ 2] −; [1′′-X-1′′,7′′- closo-C 2B 10H 11] −, [ 3] − and [1′′-X-1′′,12′′- closo-C 2B 10H 11], [ 4] − for the monoanions, whereas [1′′,2′′-X 2-1′′,2′′- closo-C 2B 10H 10] 2−, [ 2] 2−; [1′′,7′′-X 2-1′′,7′′- closo-C 2B 10H 10] 2−, [ 3] 2−; and [1′′,12′′-X 2-1′′,12′′- closo-C 2B 10H 10] 2−, [ 4] 2− for the dianions (where X = 3,3′-Co-8-(CH 2CH 2O) 2-(1,2-C 2B 9H 10)-1′,2′-(C 2B 9H 11)). 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.