Four copper(I) complexes of the ligand di(2-pyridyl)ketone (dpk) were synthesized using Cu(I)Cl, Cu(I)Br, Cu(I)CN and Cu(I)I in MeCN solution and under solvent-free conditions. The solid compounds show a reaction when mixed without solvent, which is indicated by a rapidly occurring color change. The resulting products were characterized by IR spectroscopy, MS and single crystal X-ray diffraction. In case of the Cu(I)Cl, a 1:2-complex is formed, showing a six-membered, cyclic Cu3X3-unit with quasi-boat confirmation. With Cu(I)Br, Cu(I)CN and Cu(I)I, 1:1-complexes are obtained. The Cu(I)Br and Cu(I)I complexes are binuclear and bridged by bromide and iodide anions respectively, resulting in Cu2Br2/ Cu2I2 halide-bridged square dimers. The copper(I) cation and the cyanide anion of the Cu(I)CN dpk complex are forming a one-dimensional chain bridged by the cyanide groups. The structures were further characterized by Hirshfeld analysis, showing the weak interactions in the crystal, which are consistent with the observed physical properties.