University of Texas

CH 431

Physical techniques are widely used to obtain structural information at a molecular level in both organic and inorganic chemistry. A quick and convenient laboratory bench-top spectroscopic analysis of a sample will often allow chemists insight into a structural problem without recourse to single crystal X-ray diffraction study. Vibrational spectroscopy is one such spectroscopic technique. Functional groups within a molecule vibrate at characteristic frequencies (group frequencies) and in doing so absorb radiation in the infrared (IR) region of the electromagnetic spectrum, 4000 - 200 cm-1 . Mononuclear metal carbonyl complexes are well suited to study by IR spectroscopy since intense absorptions due to the CO oscillations usually occur in the range 2100-1750 cm-1 . Furthermore, this region is also generally free from interference from absorptions due to other functional groups