The first pentanuclear complexes of formula {Dy[Cu(apox)(2)[Cu(apox)(H2O)](2)} [ClO4](3) . 7H(2)O (1), {Ho[Cu(apox)][Cu(apox)(H2O)](3)} [PF6](3) . 4.5H(2)O (2), {Gd[Cu(apox)](2)[Cu(apox)(H2(O))(2)}[ClO4](3) . 7H(2)O (3) and {Gd[Cu(apox)][Cu(apox) (H2O)(3)}[PF6](3) . 4.5H(2)O (4) (H(2)apox = N,N’-bis(3-aminopropyl)oxamide) have been synthesized. The crystal structures of complexes 1 and 2 have been determined by X-ray diffraction methods. Complexes 3 and 4 are isostructural with 1 and 2, respectively. Crystallographic data are as follows : 1 and 3, monoclinic, space group C2/c and Z = 4, with a = 14.646(6) Angstrom, b = 29.496(7) Angstrom, c = 16.002(7) Angstrom, and beta = 111.76(2)degrees for 1 and a = 14.523(6) Angstrom, b = 29.441(6) Angstrom, c = 15.925(8) Angstrom, and beta = 111.90(4)degrees for 3; 2 and 4, triclinic, P (1) over bar, and Z = 2, with a = 14.346(2) Angstrom, b = 14.454(2) Angstrom, c = 18.107(4) Angstrom, alpha = 90.95(2)degrees, beta = 110.75(2)degrees, and gamma = 106.77(2)degrees for 2 and a = 14.365(6) Angstrom, b = 14.496(5) Angstrom, c = 18.172(7) Angstrom, alpha = 91.27(3)degrees, beta = 110.74(3)degrees, and gamma = 106.67(3)degrees for 4. A tripositive ion is present in these structures, the electroneutrality being achieved by three uncoordinated perchlorate (1) or hexafluorophosphate (2) anions.The lanthanide cations are eight-coordinate with a pseudo-square-antiprismatic environment formed by carbonyl oxygen atoms from two [Cu(apox)] and two Cu(apox)(H2O)] (1) and one [Cu(apox)] and three [Cu(apox)(H2O)] (2) bidentate ligands. The temperature dependence of the magnetic susceptibility of complexes 1-4 was investigated in the range 1.8-300 K. The ligand-field effect, as well as the mixing of the foe-ion states in Dy-III and Ho-III, make extremely difficult the analysis of the overall antiferromagnetic interaction which is observed for complexes 1 and 2. The magnetic susceptibility data for complexes 3 and 4 have shown that the ground-state spin for the [(GdCu4II)-Cu-III] unit is S = 11/2, the Gd-III-Cu-II interaction being ferromagnetic with an interaction parameter J(GdCu) = 0.85 cm(-1) (the interaction Hamiltonian is of the form H = -JS(A) . S-B). The field dependence of the magnetization at 2 K of 3 and 4 confirms the nature of the ground state and of the Gd-III-Cu-II interaction. The influence of the topology and of the type of bridging ligand on the nature and magnitude of the magnetic interaction in the Gd-III-Cu-II pair is analyzed and discussed in light of available magnetostructural data.