The crystal structures of three copper(II) complexes with phenoxyisobutyric acid (PIBAH) and p-chlorophenoxyisobutyric acid (PCIBAH) have been determined by X-ray diffraction. Tetra-μ-[2-methyl-2-(4-chlorophenoxy)-propanoato-O,O′]-bis[2-amino-pyrimidine)copper(II)], [Cu2(PCIBA)4(2-aminopyrimidine)2]2 (1) is a centrosymmetric tetracar☐ylate bridged dimer [Cu⋯Cu, 2.689(2)Å] with the nitrogens of the 2-aminopyrimidine molecules occupying the axial positions [CuN, 2.198(7)Å]. Tetraaquacopper(II) tri-μ-[2-methyl-2-phenoxypropanoato-O,O′]-bis[(2-methyl-2-phenoxypropanoato(copper(II)], [Cu(H2O)4]2+] {[Cu2(PIBA)5]−}2, (2), is a disordered precursor of the stable structure (3), [Cu(H2O)5]2+ {[Cu2(PIBA)5]−·4H2O, consisting of centrosymmetric square planar [Cu(H2O)4]2+ cations and tris(car☐ylate)-bridged dimer anions [Cu⋯Cu, 2.85(1)Å] (2). The fourth position of each square planar dimer ‘end’ is occupied by a car☐ylate oxygen of a PIBA molecule which also provides the ether oxygen capping each axial dimer site [CuO, 2.15(4), 2.19(5)Å]. This completes a five-membered chelate ring. A symmetrical array of eight hydrogen bonds link the four waters of the [Cu(H2O)4]2+ cation to the car☐yl oxygens of both the capping PIBA ligands of the two dimeric anions. Structure (3) has essentially identical [Cu2(PIBA)5]− dimer anions [Cu⋯Cu, 2.929(1)Å] and hydrogen-bonding interactions with the tetraaquacopper(II) cations. However, water molecules partially occupy the octahedral sites of these cations [CuO, 2.46(1)Å], as well as a number of lattice sites in the crystal.