Exploration Of Efficient Main-Group Bond Forming Reactions

Molecules containing main-group bonds are of great importance to our everyday lives and are found in different applications ranging from pharmaceutical to materials chemistry. Specifically, phosphorus-based molecules are of particular importance due to the diminishing global supply, with current trends indicating that our use will quickly outgrow what is available. Thus, it is imperative that synthetic chemists discover efficient transformations to increase the recyclability of phosphorus. One method at our disposal is hydrophosphination, which offers a facile and atom economical approach to produce phosphorus-based compounds. Photo-enhanced hydrophosphination has been an area of interest due to the use of light as a resource. The parent and decamethyl zirconocene dichloride compounds, Cp2ZrCl2 and Cp*2ZrCl2, were investigated as potential catalysts. These compounds were irradiated in the near ultraviolet (UV) resulting in the successful hydrophosphination of styrene substrates and activated alkenes. Irradiation appears to induce homolysis of the Cp or Cp* ligand, resulting in radical hydrophosphination. Successful detection of this radical reactivity was achieved by monitoring for EPR signals with in situ irradiation, a methodology proving to be general for the determination of radical versus closed-shell reactivity in transition-metal photocatalysis. While these complexes were competent catalysts for this transformation, a more active catalytic system was needed. A series of group I tert-amylate complexes, MOtAmyl (M = Li–Cs), were investigated as highly active, yet inexpensive and commercially available catalysts for hydrophosphination. Additionally, the utility of this catalytic reaction is broadened by investigating the synthesis of phosphorus-based ligands. In contrast to molecules containing P–C bonds, the investigation of other main-group element bond-forming reactions are investigated, particularly those of group 13-15 (III/V). A series of Lewis acid-base adducts are synthesized and isolated, and their thermolysis behavior and applications for the facile synthesis of group 13-15 ceramics are discussed.