The reaction and solvation dynamics of organometallic compounds

Ultrafast laser spectroscopy provides a tool by which a chemical reaction may be monitored from the initiation to the formation of the final products. This method allows for the unambiguous determination of the identity of reactive intermediates which may not be observed in traditional mechanistic studies. The barriers and reaction mechanism may also be determined from the kinetic data. Unfortunately, the transient nature of the intermediates observed in ultrafast experiments have lifetimes which are too short for traditional characterization. In these cases, electronic structure theory and molecular dynamics methods may be utilized to study these species.; The findings presented in this thesis are based upon experimental and theoretical results on the reaction and solvation dynamics of transient intermediate species which are important in a variety of organometallic chemical systems. First, the mechanism of several bond activation reactions have been examined using femtosecond UV pump/IR probe spectroscopy. A special emphasis has been placed on the effect that the organometallic intermediate spin state has on the reaction mechanism. It has been found that triplet species do not coordinate strongly with alkanes or the alkyl group of reactive solvents, which leads to increased reaction rates compared to those observed with similar singlet intermediates. The factors that govern the reactivity of high spin species have also been elucidated. These results are supported by ab initio and Density Functional Theory (DFT) calculations, which qualitatively reproduce and explain the trends in the observed experimental results.; In order to examine the microscopic aspects of solvent/solute interactions, classical as well as mixed quantum classical molecular dynamics simulation programs have been developed. These methods have been used to study the solvation dynamics of organometallic charge transfer complexes as well as excess electrons in frozen glasses, gas clusters and at surface interfaces. These results have shown that excited states of organometallic chromophores which have localized charge densities are preferentially solvated in polar solvents. The study of the dynamics of the excess electron have shown that the solvation dynamics depend on the periodicity of the bath. Using the method of Transition Path Sampling, a general mechanism of ligand rearrangement has been proposed. Overall, these results complement existing experimental results and provide a more detailed picture of solvent/solute interactions that may not be determined from experimental studies.