Vibrational overtone spectroscopy of pi-bonded organometallic complexes and corresponding hydrocarbon ligands.

摘要

Vibrational overtone spectroscopy provides information concerning the structure and dynamics of molecules with high internal energy. For many small molecules, which have been studied by this technique, the interpretation of the overtone spectra was simple. However, assignment of the overtone transitions for larger multiconformer molecules still remains a complicated matter. In this present study a new method for vibrational assignment of overtone spectra is introduced. This method combines correlations between the calculated bond lengths and overtone transition energies for particular local mode oscillator types and results of geometry optimization to predict the overtone spectra for the studied molecule. Comparison of the predicted and experimental spectra allows assignment to overtone transitions. The performance of this new method for different types of oscillators and the obtained vibrational assignments are discussed. In the second part of this work, a vibrational overtone spectroscopy was used to investigate changes in the vibrational behavior of conjugated olefinic hydrocarbons when they bind to a transition metal forming {dollar}pi{dollar}-bonded organometallic complexes. For selected ligand-complex pairs the vibrational overtone spectra of complexes were recorded and compared to the spectra of pure ligands. Based on this comparison the influence of transition metals on ligands was determined. The background information about vibrational overtone spectroscopy, ab initio computational methods and {dollar}pi{dollar}-bonded organometallic complexes is provided in Chapter 1. The experimental methods and sample preparations are described in Chapter 2. The proposed new method for vibrational assignments is discussed in Chapter 3. Chapter 4 presents results and discussion concerning vibrational overtone spectroscopy of organometallic complexes and corresponding hydrocarbon ligands.