In the last ten years, a considerable research effort has been devoted to the synthesis of nanometer scale magnetic systems with the ultimate goal to reduce the size of the magnetic units that store information. Different approaches have been used to obtain single-domain magnetic particles, but the beginning of the 1990’s marked the discovery of Single-Molecule Magnets (SMMs) [1], which created the hope to store information on a single molecule [2]. Last 20 years, numerous SMMs have been discovered, and many scientific teams currently works on the design of new systems with improved magnetic characteristics. We develop here a rational approach to the synthesis of SMMs, where the magnetic building blocks can be assembled, as in a veritable molecular magnetic-LEGO, to yield the desired magnetic properties in a rational, stepwise assembly. The idea to organize SMM and anisotropic building-blocks in coordination networks has been one of the most successful strategies and has led to the discovery of new magnetic properties including Single-Chain Magnet behavior [3]. Among various available building blocks, Schiff base complexes of Mn(III), appear to be the most promising molecular precursors since they possess an inherent magnetic anisotropy and substitutable axial positions to be connected by donor linkers. In this context, the tetradentate N1,N4-bis(salicylidene)-S-alkylisothiosemicarbazide type of ligands (H2L) possess interesting coordinating properties for a number of metal ions [4], especially for manganese ions with different oxidation states. In this presentation, a binuclear complex N1,N4-bis(salicyliden)-S-methylisothiosemicarbazidato(-2)-chloromanganese( III) will be presented and discussed. The interaction of the chloride with H2L in methanol solution affords the solvate [Mn(L)Cl(CH3OH)] which has a monomeric octahedral structure. The crystal structure changes after recrystalization of the compound from chloroform. The resulting product [Mn(L)Cl]2·2CHCl3 has a dimeric layered structure with oxygen bridges. The interatomic distance Mn-O´(1) is 2,605 Å. The angle Mn-O-Mn´makes 99.26° and testifies a rhombic form of the quadrangle MnO(1)Mn´O´ (1) with a distance Mn-Mn´- 3,456 Å. The dimmer exhibits intradimer ferromagnetic exchange and displays frequency dependence of ac magnetic susceptibility, showing single-molecule-magnet (SMM) behavior. This SMM can serve as a building block for rational design of new Single-Chain Magnets.