The increasing of nuclearity of complexes that may serve as precursors for new functional materials with advanced properties is one of the main tasks of modern coordinative chemistry. Our study was aimed at obtaining of binuclear complexes by substitution of sulfanilamidic ligand of [Co(N3)(DH)2(L)] complex (DH – monoanion of dimethylglioxime; L – sulfanilamide) with 4,4′-bipyridine (bpy). On interaction of [Co(N3)(DH)2(L)] complex with 4,4′-bipyridine (1:1 ratio) the mononuclear complex [Co(N3)(DH)2(bpy)] (1) has been obtained, whereas by using a 2:1 ratio of reagents the binuclear [(Co(N3)(DH)2)2(bpy)]·H2O (2) has been prepared. Crystal and molecular structures of compounds 1 and 2 were determined by single X-ray analysis. Compound 1 crystallizes in monoclinic space group P21/n, a = 8.0905(6), b = 13.4459(9), c= 19.161(2)Å, β = 97.712(8)°. Atom of cobalt is coordinated in equatorial plane by two monodeprotonated DH ligands, monodentate N3 - anion and bpy molecule occupy the apical trans-positions, resulting in octahedral N6 surrounding of metal (Fig. 1). The ··· stacking interaction between about parallel aromatic moieties of bpy ligands with centroid···centroid separation 3.741Å unites monomeric complexes of 1 in centrosymmetric dimer. Crystals of compound 2 are triclinic, P-1, a = 7.8421(5), b = 14.5713(6), c = 15.5422(6) Å, α = 91.330(3), β = 90.975(4), γ = 95.208(4). Crystal structure of 2 reveals two similar but symmetry independent centrosymmetric binuclear complexes, in which the exo-bidentate bpy ligand bridges two [(Co(N3)(DH)2)] fragments, resulting again in octahedral coordination of the metal (Fig. 2). In the crystal of 2 solvate water molecules join the symmetry independent dimeric complexes in chain due to hydrogen bonds O1W···…N6A (2.789(8)Å) and O1W···…O1B (2.878(7)Å). The analysis of crystal structure of 2 reveals that packing of complexes forms infinite channels along a crystallographic axes filled by Hbonded water molecules.figureFig. 1. ···... stacking interactions in 1figureFig. 2. Fragment of the structure 2