Synthesis of functional derivatives of the [3,3′-Co(1,2-C2B9H11)2]− anion

A series of various functional derivatives of the cobalt bis(1,2-dicarbollide) anion [8-XCH2CH2OCH2CH2O-3,3′-Co(1,2-C2B9H10)(1′,2′-C2B9H11)]− (X=OH, NH2, and CH(NH2)COOH) were prepared by the ring-opening reactions of [8-O(CH2CH2)2O-3,3′-Co(1,2-C2B9H10)(1′,2′-C2B9H11)] with different nucleophiles followed by functional group interconversion reactions. Acidic hydrolysis of [8-NCCH2CH2OCH2CH2O-3,3′-Co(1,2-C2B9H10)(1′,2′-C2B9H11)]− resulted in the shorter-chain alcohol [8-HOCH2CH2O-3,3′-Co(1,2-C2B9H10)(1′,2′-C2B9H11)]−. Structures of (Bu4N)[8-AcNHC(COOEt)2CH2CH2OCH2CH2O-3,3′-Co(1,2-C2B9H10)(1′,2′-C2B9H11)] and [8-(1-C5H5N)CH2CH2OCH2CH2O-3,3′-Co(1,2-C2B9H10)(1′,2′-C2B9H11)] were determined by the single crystal X-ray diffraction method. Perspectives of application of functionalized cobalt bis(1,2-dicarbolide) derivatives in nuclear medicine are discussed.