The use of di-2-pyridyl ketone oxime, (py)pkoH, and phenyl 2-pyridyl ketone oxime, ppkoH, in copper(II) hexafluoroacetylacetonate chemistry is reported. The reaction of CuCl 2·2H 2O with one and two equivalents of ppkoH and Na(hfac), respectively, in CH 2Cl 2 affords the dinuclear complex [Cu 2(hfac) 2(ppko) 2] ( 1) in excellent yield. The replacement of ppkoH by (py)pkoH gives the isostructural compound [Cu 2(hfac) 2{(py)pko} 2] ( 2) in good yield. The Cu II atoms in both 1 and 2 are doubly bridged by the oximate groups of two η 1:η 1:η 1:μ 2 ppko − and (py)pko − ligands, respectively. The bridging Cu–(R–NO)–Cu′ units are not planar, with the torsion angles being 23.2° ( 1) and 20.3° ( 2). A bidentate chelating hfac − ligand completes five-coordination at each square pyramidal metal ion. The hfac −-free reaction system CuCl 2·2H 2O/(py)pkoH/NEt 3 (1:2:1) gives instead the mononuclear complex [CuCl{(py)pko}{(py)pkoH}] ( 3) in very good yield. The Cu II atom is coordinated by two N, N′-bidentate (py)pko −/(py)pkoH chelates and a monodentate chloride anion resulting in a distorted square pyramidal geometry around the metal center. Variable-temperature, solid-state dc magnetic studies were carried out on the representative dinuclear complex 1 in the 2.0–300 K range. The data indicate a very strong antiferromagnetic exchange interaction and a resulting S = 0 ground state, which is well isolated from the S = 1 excited state. The J value of −720 cm −1 was derived from the fitting of the experimental data using the Hamiltonian H = − J( S 1 · S 2).