Two new phenylmalonate-bridged copper(II) complexes with the formulas [Cu(4,4'-bpy)(Phmal)]center dot 2nH(2)O (1) and [Cu(2,4'-bpy)(Phmal)(H2O](n) (2) (Phmal = phenylmalonate dianion, 4,4'-bpy = 4,4'-bipyridine, 2,4'-bpy = 2,4'-bipyridine) have been synthesized and characterized by X-ray diffraction. Complex 1 crystallizes in monoclinic space group P2(1), Z = 4, with unit cell parameters of a = 9.0837(6) angstrom, b = 9.3514(4) angstrom, c = 11.0831(8) angstrom, and beta = 107.807(6)degrees, whereas complex 2 crystallizes in orthorhombic space group C2cb, Z = 8, with unit cell parameters of a = 10.1579(7) angstrom, b = 10.3640(8) angstrom, and c = 33.313(4) angstrom. The structures of 1 and 2 consist of layers of copper(II) ions with bridging bis-monodentate phenylmalonate (1 and 2) and 4,4'-bpy (1) ligands and terminal monodentate 2,4'-bpy (2) groups. Each layer in 1 contains rectangles with dimensions of 11.08 x 4.99 angstrom(2), the edges being defined by the Phmal and 4,4'-bpy ligands. The intralayer copper-copper separations in 1 through the anti-syn equatorial-apical carboxylate-bridge and the 4,4'-bpy molecule are 4.9922(4) and 11.083(1) angstrom, respectively. The anti-syn equatorial-equatorial carboxylate bridge links the copper(II) atoms in complex 2 within each layer with a mean copper-copper separation of 5.3709(8) angstrom. The presence of 2,4'-bpy as a terminal ligand accounts for the large interlayer separation of 15.22 angstrom. The copper(H) environment presents a static pseudo-Jahn-Teller disorder which has been studied by EPR and low-temperature X-ray diffraction. Magnetic susceptibility measurements of both compounds in the temperature range 2-290 K show the occurrence of weak antiferromagnetic [J = -0.59(1) cm(-1) (1)] and ferromagnetic [J = +0.77(1) cm(-1) (2)] interactions between the copper(II) ions. The conformation of the phenylmalonate-carboxylate bridge and other structural factors, such as the planarity of the exchange pathway in 1, account for the different nature of the magnetic interaction.