23.1 The Transition Metals

Transition Metals utilize their valence d-orbitals to form coordination complexes, which have characteristics important to industry, technology, and medicine. Coordination complexes exist in every color of the rainbow and can be found in jewelry, steel, paints, anticancer drugs, and photographic films. Most catalysts contain transition metal complexes and they are commonly used in the pharmaceutical industry. There two areas are vitally important to research chemists and are rapidly growing. A better understanding of the fundamentals of coordination complexes will help you understand current materials and will help chemists improve how these materials function.

In the early days, chemists were fascinated by transition metal complexes due to their color. The color of these complexes depends heavily on the d electron count of the transition metal, and the energy levels in the complex ions.

23.1 Transition Metals and Coordination Complexes

Being able to properly interpret the properties of the electromagnetic spectrum will allow us to interpret how our eyes detect color.

23.1 The Electromagnetic Spectrum and Color

The discreet nature of the energy levels in molecules allows us to determine the energy it would take to excite an electron from an energy level of lower energy to one of higher energy. If this excitation falls in the visible range of the electromagnetic spectrum, our eye will detect color.

23.1 Orbital Energies

Chemists are able to measure the wavelength of light a material absorbs using a UV-Vis Spectrometer, and by measuring which wavelengths of radiation are absorbed and which are not, we can gain valuable information on a molecules electronic excitations, or electronic structure.

23.1 UV-Vis Spectroscopy

23.1 UV-Vis Spectroscopy (cont.)

Keep in mind that a transition metal atom has very different properties than when it is the central atom in a coordination complex. This is due to the difference in how the electrons fill the orbitals to achieve the lowest energy configuration possible.

23.1 Electron Configurations of Transition Metal Complexes