The reactions of di-2-pyridyl ketone (Dpk), an interesting polydentate ligand, with metal ions have recently attracted considerable attention. A number of nucleophiles, including water and alcohols, have been shown to add to the carbonyl group upon coordination of the pyridyl groups to metal. A literature review about complexes synthesised using dpk ligand is presented in Chapter 2. A total of 20 compounds have been examined using single crystal X-ray diffraction which was an accurate technique to provide detailed information about their internal structure of crystals including all data about unit cell dimensions, bond length and bond angles. Lanthanide triangles Dy and Er have been studied and described in Chapter 3. Chromium and Vanadium clusters have been described in Chapter 4. Also, Scandium and Yttrium complexes have been formed and described in Chapter 5. Conclusions drawn regarding in Chapter 6 and four previously published structures are presented in the Appendix chapter.