Theoretical studies on the reactivity of organoboron compounds, transition-metal boryl complexes, and acyclic silylene have been reported with the aid of DFT calculations in this thesis. We have unraveled reaction mechanisms based on experimental results and have made useful predictions on some cases. For organoboron compounds, the reactivity is dependent on the Lewis acidity of the empty p orbital of the boron center. Once the empty p orbital of the boron center is occupied by a nucleophile, the remaining three bonds around the boron center could be activated and undergo further migrations/transformations. This important insight helps us understand phosphine-catalyzed trans-hydroboration of alkynoate esters (Chapter 2), the reactivity of diborane compounds toward organic azides (Chapte...[ Read more ]

Theoretical studies on the reactivity of organoboron compounds, transition-metal boryl complexes, and acyclic silylene have been reported with the aid of DFT calculations in this thesis. We have unraveled reaction mechanisms based on experimental results and have made useful predictions on some cases. For organoboron compounds, the reactivity is dependent on the Lewis acidity of the empty p orbital of the boron center. Once the empty p orbital of the boron center is occupied by a nucleophile, the remaining three bonds around the boron center could be activated and undergo further migrations/transformations. This important insight helps us understand phosphine-catalyzed trans-hydroboration of alkynoate esters (Chapter 2), the reactivity of diborane compounds toward organic azides (Chapter 3), the reactivity of borole compounds toward epoxides (Chapter 4), and the reactivity of borole cycloaddition reactions (Chapter 5). For transition-metal boryl complexes, we have reported theoretical studies on the reactivity of a (NHC)Au-diarylboryl toward polar multiple bond molecule (Chapter 6) and Rh-catalyzed deoxygenative borylation of ketones (Chapter 7). Based on these studies and a series of previous work of our group on the reactivity of (NHC)Cu-boryl complexes, we have systematically compared the reactivities of different metal-boryl complexes toward phenyl aldehyde (Chapter 8), and pointed out that in addition to that the metal-boryl σ-bonding electrons could play the nucleophilic role, the electrophilicity of “empty” p orbital on the boron center of a boryl ligand, and the nucleophilicity of d electron pairs of the metal center could initiate a reaction as well. Apart from boron chemistry, theoretical studies on the reactivity of a silylene compound toward small gas molecule (CO, CO₂ and N₂O) activation is also reported (Chapter 9), our study has provided an in-depth understanding of the acyclic silylene’s single-site ambiphilic reactivity.