COBALT(III) COMPLEXES OF CYSTEINE AND CYSTEINE DERIVATIVES

A series of new cobalt(III) complexes of the formulation Co(en)2AAn+, where en is ethylenediamine and AA is -SCH2CH-(NH2)COO- (Cy); -SCH2CH(NH2)COOH (HCy); -SCH2CH(NH2)COOC2H5 (OECy), and CH3SCH2CH(NH2)COO- (SMCy), has been prepared and the compounds have been characterized using elemental analyses, conductivity and molecular weight measurements, visible and infrared spectral data, and nmr studies. The coordination of cysteine in Co(en)2Cy+ is through amino and mercaptide groups. The carboxylate group of cysteine in this complex is not coordinated; it is protonated upon treatment with acid. Ethyl cysteinate is coordinated through the amino and mercaptide groups in Co(en)2-OECy2+ whereas S-methyl-L-cysteine is coordinated through amino and carboxylate groups in Co(en)2SMCy2+. Methylation of the mercaptide in Co(en)2(Cy)+ results in a novel rearrangement from N and S chelation to N and O chelation. © 1969, American Chemical Society. All rights reserved.