The reaction of cobalt(II) acetate tetrahydrate with dithiaalkyl-substituted triazene 1-oxides [MeN(O)-NNHC6H4S]2(CH2)x, H2MexL (x = 2, 3) affords Co(II)(MexL) (2), which undergoes facile oxidation by hydrogen peroxide, furnishing [Co(III)(MexL)]ClO4.CH2Cl2(3). In these complexes the ligands act in a hexadentate manner, and the coordination spheres are of the type CoS2N2O2. When Co(Me2L)+ is treated with base, the green complex Co(III)(Mel)(Mel’) (4) is formed through cleavage of the coordinated ligand into two tridentate parts via scission of a C-S bond. The coordination sphere is Co(SNO)(SNO), one sulfur site being thioether and the other being thiolate. On the other hand a similar treatment of Co(Me3L)+ affords the organocobalt(III) complex Co(III)(Me3L’) (5) formed by the displacement of a thioether site by a carbanionic site in the coordination sphere which becomes CoSCN2O2. The same reactions can be achieved by reacting Co(MexL) with alkali in the presence of oxygen. These remarkable homolog-selective transformations have been rationalized, and other examples fitting into the rationale are also presented. Cleavage occurs when the thioether chelate ring activated via alpha-methylene deprotonation is five-membered and an organocobalt(III) complex is formed when it is six-membered. The complexes have been characterized with the help of spectroscopy (UV-vis, H-1 NMR) and X-ray crystallography. The X-ray structures of four complexes are reported : (i) Co(Me3L), crystal system orthorhombic, space group P2(1)212(1), a = 7.871(2) angstrom, b = 9.777(4) angstrom, c = 25.942(10) angstrom, V = 1996(1) angstrom3, Z = 4, R = 5.02%, R(w) = 5.19%; (ii) [Co(Me3L)]ClO4.CH2Cl2, crystal system triclinic, space group P1BAR; a = 9.849(5) angstrom, b = 11.666(6) angstrom, c = 13.354(7) angstrom; alpha = 102.33(4)degrees, beta = 103.24(4)degrees, gamma = 108.47(4)degrees, V = 1346(1) angstrom3, Z = 2, R = 4. 54%, R(w) = 4.38%; (iii) Co(Me1)(Me1’), crystal system monoclinic; space group P2(1)/n, a = 9.445(5) angstrom, b = 18.650(8) angstrom, c = 11.284(6) angstrom, beta = 100.90(4)degrees, V = 1952(1) angstrom3, Z = 4, R = 4.74%, R(w) = 4.72%; (iv) Co(Me3L’).CHCl3, crystal system monoclinic, space group P2(1)/n, a = 12.818(7) angstrom, b = 14.597(8) angstrom, c = 13.194(6) angstrom, beta = 97.67(4)degrees, V = 2447(2) angstrom3, Z = 4, R = 4.03%, R(w) = 4.07%.