Two new mono-aqua-bridged dinuclear Cu(II) complexes of tridentate NNO Schiff bases, [Cu₂(μ-H₂O)L¹₂(H₂O)₂](BF₄)₂·2H₂O <strong>(1)</strong> and [Cu₂(μ-H₂O)L²₂(H₂O)₂](BF₄)₂·2H₂O <strong>(2)</strong> where HL¹ = 2-[1-(2-dimethylamino-ethylimino)-ethyl]-phenol and HL² = 2-[(2-dimethylamino-ethylimino)-methyl]-phenol were synthesized. Both the complexes were characterized by single-crystal X-ray diffraction analyses and variable-temperature magnetic measurements. For both the complexes each Cu(II) ion is in a square-pyramidal environment being bonded to three atoms from the tridentate NNO Schiff base and a terminal H₂O molecule in the equatorial plane; a second H₂O ligand acts as a bridge between the two Cu(II) centres through the axial positions. Hydrogen bonds between the terminal H₂O ligand and the Schiff base of the adjacent centre complete the intra-dimer linkages. Variable-temperature (4–300 K) magnetic susceptibility measurement shows the presence of significant antiferromagnetic coupling for both the complexes (<i>J </i>= −12.2 and −12.5 cm⁻¹, respectively, for <strong>1</strong> and <strong>2</strong>), mediated mainly through the intra-dimer H-bonds.< Leer menos