Two 3D supramolecular complexes [Cu(2)(trans-oxpn)(phth)](n)().2nH(2)O, 1, and [Cu(2)(trans-oxpn)(&mgr;-OH)(&mgr;-H(2)O)](n)()Br(n)().2nH(2)O, 2 [H(2)oxpn = N,N'-bis(3-aminopropyl)oxamide, phth = phthalate], were synthesized and characterized by single-crystal X-ray crystallography, thermal analyses, and magnetic measurements. 1 crystallizes in the monoclinic space group P2(1)/c with a = 8.578(2) Å, b = 15.596(2) Å, c = 15.657(2) Å, beta = 101.29(2) degrees, Z = 4; 2 crystallizes in the trigonal space group R&thremacr;c with a = 15.266(2) Å, b = 15.266(2) Å, c = 34.953(5) Å, and Z= 18. The neutral 2D sheetlike coordination polymer [Cu(2)(trans-oxpn)(phth)](n)() in 1 contains alternate trans-oxamidate and phthalate bridges and then is joined together by H(2)O molecules via the hydrogen bond linkage Cu(oxpn).H(2)O.H(2)O.(oxpn)Cu to produce a 3D supramolecular structure. The cationic chains [Cu(2)(trans-oxpn)(&mgr;-OH)(&mgr;-H(2)O)](n)()(n)()(+) in 2 contain alternate trans-oxamidate, &mgr;-OH, and &mgr;-H(2)O bridges and are arranged in three directions, intersecting with one another to yield an extended network via the interchain hydrogen bonds formed by metal-coordinated OH(-) with the linkages Cu(oxpn)-OH.OH-Cu(oxpn). Magnetic calculations showed the presence of antiferromagnetic exchange interactions for both complexes. The 2D magnetic coupling system of 1 was simplified into interacting dimers Cu(trans-oxpn)Cu, with the coupling via phth as an interdimer interaction and the data were interpreted with a modified Bleaney-Bowers equation leading to J = -456.7 cm(-)(1) and theta = 22.0 K. 2 was analyzed qualitatively by an alternating chain model taking into account the interchain interaction in a molecular model with J(1) = -309.6 cm(-)(1), J(2) = -63.5 cm(-)(1), and theta = -12.9 K, where J(1) and J(2) denote the coupling constants of the bridges oxamidate and &mgr;-OH, respectively.