Theoretical Studies On Thermodynamic Properties Of The Hydrides

Organic hydride donors are one class of very important organic compounds that can provide hydride anions in chemical and biochemical reactions. From the view of physical organic chemistry, very few papers were found to report the determination of the thermodynamic driving forces of the compounds as organic hydride donors to release hydride anion in solution so far. In this study, we employ theoretical calculations to study the thermodynamic driving forces of the compounds.In the first chapter, we reviewed the back ground of the organic hydride donor and the studies on its thermodynamics and kinetics. Then we introduced the structure-activity relationship of compounds.In the second chapter, several computational methods were introduced, including quantum chemistry method, and most importantly, the ONIOM method.In the third chapter, the new developed ONIOM/G4 method was used to accurately predict the hydricities of organic hydride donors in acetonitrile. In this work we successfully established an effective tool with high precision (1.8 kcal/mol) for predicting the hydricities. Based on the data we obtained, we systematically studied the structure-activity relationships in hydricities of organic hydride donors.In the fourth chapter, DFT method was used to predict the redox potentials of organic hydride donors, whose reliability has been tested against almost all the available experimental data. By using this method, the important thermodynamic properties of organic hydride donors were investigated and the mechanisms of hydride transfer progress were explained.In the fifth chapter, we construct a complete ylide thermodynamic stability scale on the basis of accurately calculated C-H pKa's of ylide precursors. For the first time, corresponding substituent effects were rationalized systematically.In the sixth chapter, DFT method was used to predict the BDE of Environmental Pollutants. Armed with this powerful tool, the C-Cl bond dissociation enthalpies (BDEs) of some persistent environmental pollutants are calculated. Further, the substituent effects are discussed.