The "direct synthesis" approach, namely one-pot reaction of metal powders and ammonium salt with a methanol solution of a polydentate Schiff base (H2L) formed in situ from salicylaldehyde and ethanolamine, has been successfully used for the preparation of the new heterometallic compounds [Cu3Mn(L)4(CH3OH)3]I3 (1), [Cu3Mn(L)4(CH3OH)3(H2O)]NCS·H2O (2), [Cu3Mn(L)4(CH3OH)(H2O)2.55]Br·0.45H2O (3) and [Cu3Mn(L)4(H2O)3.4]BF4·0.6H2O (4). Crystallographic analysis revealed that 1-4 are based on the tetranuclear core {CuMnIII(μ3-O)4} where the metal centres are joined by the oxygen bridges of Schiff base ligands forming a cube-like arrangement. The novel heterometallic compound [Cu3Mn(L)4(CH3OH)3]2[Mn(NCS)4]·2CH3OH (5) has been obtained by the "building block" approach using the reaction of [Cu(HL)2] with manganese acetate and NH4NCS in methanol. The crystal structure of 5 revealed the {CuMnIII(μ-O)2(μ3-O)2} metal core which can be viewed as a double open cube. In spite of a similar {Cu3MnO4} atom set in the cores of 1-5, the complexes show rather different molecular structures and significantly differ by the number and combinations of coordinated CH3OH/H2O solvent molecules. Variable-temperature (2-300 K) magnetic susceptibility along with variable-field magnetization measurements of 1-5 showed a decrease of the effective magnetic moment value at low temperature, indicative of the antiferromagnetic coupling of medium size (-55 to -22 cm-1). For these systems resembling a compressed prism the coupling constant in walls J4 correlates with the averaged bonding angles in walls α: J4vs. α develops approximately according to a straight line.