The flexible quadridentate ligand 1,8-diamino-3,6-dithiaoctane (eee), having the donor atom sequence nitrogen-sulfursulfur-nitrogen, forms monomeric octahedral complexes with cobalt(III). The following complex cations have been prepared and characterized: Co(eee)Cl2,+, Co(eee)Br2,+, Co(eee)CO3,+, Co(eee)(NO2)2,+, and Co(eee)(NH2CH2COO)2+. Although three geometric isomers are theoretically possible, the presence of thioether donors appears to induce an extreme geometric specificity and we have succeeded in characterizing only the symmetrical cis isomer in which the primary amine groups are coordinated trans to each other. Methods of preparation, chemical interconversions, electronic adsorption spectra, infrared spectra, and nuclear magnetic resonance data are presented and discussed. © 1969, American Chemical Society. All rights reserved.