The parent ligands used are bis(salicylaldimines), C6H4(OH)CH=N(CH2)(2)S(CH2)(2)N(CH2)(2)N=CH(OH) (abbreviated H(2)sxL, x = 2, 3). The complexes [Co-III(sxL)]ClO4, 5 (x = 2) and 6 (x = 3), were prepared in air from H(2)sxL and cobalt(II) acetate tetrahydrate and sodium perchlorate. The X-ray structure of 5 has revealed CoO2N2S2 coordination-the asymmetric unit consisting of a racemic pair of molecules. In acetonitrile solution, 5 and 6 react with sodium hydroxide affording respectively Co-2(III)(sl)(2)(sl’)(2), 7, and Co-III(s3L’), 8. The ligands (sl)(2-) and (sl’)(-) are deprotonated salicylaldimines of NH2(CH2)(2)SH and NH2(CH2)(2)SCHCH2, respectively. The ligand (s3L’)(3-) is (s3L)(2-) with one alpha-methylene proton dissociated. The X-ray structure of complex 7 has revealed the presence of the rare thiolato-bridged planar motif (Co2S2)-S-III. The coordination sphere is of type O2N2CO(mu-S)(2)CoN2O2; the thioether functions are not coordinated and remain dangling. The primary process is alpha-methylene deprotonation. In the conversion 5 --> 7, C-S cleavage occurs, followed by thiolato-bridge formation and concomitant thioether displacement. In the transformation 6 --> 8, the metal binding simply shifts from thioether to the adjacent carbanionic site. All complexes have been characterized-with the help of H-1 NMR data. Characteristic features : single azomethine signals for 5 and 6 but double signals for 7 and 8; vinyl multiplets at delta 5.93 and 5.06 for 7 and CoCH triplet at delta 4.89 (J = 9.7 Hz) for 8. Crystal data are as follows : [Co(s2L)]ClO4, crystal system orthorhombic, space group Pna2(1), a = 34.13(2) Angstrom, b = 11.191(7) Angstrom, c = 11.401(6) Angstrom, V = 4355(4) Angstrom(3), Z = 8, R = 7.38%, R(w) = 7.21%; Co-2(sl)(2)(sl’)(2).2MeCN, crystal system triclinic, space group P (1) over bar, a = 10.467(5) Angstrom, b = 13.701(7) Angstrom, c = 17.364(10) Angstrom, alpha = 96.72(4)degrees, beta = 99.68(4)degrees, gamma = 107.86(4)degrees, V = 2298(2) Angstrom(3), Z = 2, R = 8.23%, R(w) = 8.29%.