A novel dimeric Mn-II complex {[Mn(N3O2)]Cl(OH2)}(2)2Cl (2) of a macrocyclic Schiff base ligand derived from the condensation of 2,2', 6,6'-tetraacetyl-4,4'-bipyridine with 3,6-dioxaoctane-1,8-diamine in the presence of a stoichiometric amount of MnII has been prepared and characterized. The X-ray analysis of 2 reveals that the two Mn ions assume a pentagonal-bipyramidal geometry, with the macrocycle occupying the pentagonal plane and the axial positions being filled by a halide ion and a H2O molecule. Magnetic susceptibility data (2-270 K) reveal the occurrence of weak antiferromagnetic interactions between covalently tethered Mn-II-Mn-II dimeric units.