The coordination compmmds of 3d elements containing as ligand thiosemicarbazide derivatives possess imp01tant biological, analytical and physical prope1ties. The chemistiy of manganese with this type of ligands is not so much investigated. In this study we describe a new ti·ansfonnation of salicylaldehyde thiosemicaibazone (H2L) promoted by manganese ions. The state of salicylaldehyde thiosemicaibazone in solutions is depending on pH. The molecular fonn H2L persists in acidic solution, the monodeprotonated f01m HL- - in slowly alkaline solutions and the twice deprotonated fo1m L2- - in sti·ongly alkalinized solutions. The 3d elements prefer to fo1m coordination compounds with the mono- or bis-deprotonated fo1ms in neuti·al or alkaline media. The interaction of manganese(Il) cations in neuti-al conditions gives rise to the fonnation of the complex Mn(HL)2. If the reaction is realized in sti·ongly alkalinized solutions, the fo1mation of a compound of composition Mn(L}3H20 was obse1ved. The X-ray investigation of its stiucture demonsti·ated the fonnation of a binuclear complex of the composition [(MnLi)(Mn(H20)4)]·2H20 (Fig. la). Both manganese(!!) ions are hexacoordinated. The 02N2S2 coordination smTounding of Mnl may be described as disto1ied trigonal prism, while 06 geometry around Mn2 ion is an octahedron. The investigation of the inagnetic prope1ties of the manganese(Il) dimer shows a dominat antiferomagnetic interaction between parninagnetic centers. The compound is not soluble in any solvent in ine1t atinosphere. In the presence of the air oxygen, in methanol solutions the oxidation of the Mn(Il) to Mn(III) and an oxidative dimerization of the coordinated salicylaldehyde thiosemicarbazonate anion were detected. As a result, the fo1mation a new hexadentate bicompaitimental ligand coordinated to two different manganese(III) ions by 02N4 donor atoms has been obse1ved. The manganese(III) lmits [(Mn2L)(CH30)2(CH30H)2] ai·e assembled in polymer via μ₂-oxo bridges provided by methoxy groups coordinated to the metal ions. The coordination of the metal is completed up to squai·e-bipyrnmidal by methanol molecule coordinated in axial position. The general fo1mula is [(Mn2L)(CH30)2(CH30H)2]n (Fig. lb). The c1ystal engineering of the complexes, role of the hydrogen bonds and other inte1molecular interactions in stabilization of the stmctme will be discussed. Low-temperature magnetochemical investigation of the polymer indicates a fe1rnmagnetic interaction and a slow relaxation in ac susceptibility, confuming the SMM behavior of the complex.