Synthesis of functional derivatives of the [3,3′-Co(1,2-C2B2H11)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-operning reactions of [8-O(CH2CH2)(2)O-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)(2)CH2CH2OCH2CH2O-3,3'-Co(1,2-C2B9H10)(1',2'-C2B9H10)] 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. (C) 2002 Elsevier Science B.V. All rights reserved.