In this project funded by the Chemical Structure, Dynamic & Mechanism B Program of the Chemistry Division, Professor Guy Bertrand of the Chemistry and Biochemistry Department at the University of California - San Diego (UCSD), will prepare original ligands for transition metal catalysts and novel stable radicals. The myriad of catalytic applications requiring electron-rich ligands will benefit from the group 13 element species that will be synthesized. Radicals are involved in numerous chemical and biological processes, and their stabilization will allow for a better understanding of their properties. This project is at the interface between physical, organic, inorganic and organometallic chemistry; therefore it is well suited to the education of scientists at all levels. The laboratory of the principal investigator is a joint venture between UCSD and the French National Centre for Scientific Research. It serves to promote the exchange of undergraduates and graduates between UCSD and European Universities.
For years the "directing L" ligands of transition metal catalysts were based on the elements of groups 15 and 16. The introduction of N-Heterocyclic Carbenes, and thus of ancillary ligands based on a group 14 element, has generated many breakthroughs. This is the result of the strong sigma-donor properties of carbenes, which are due to the lower electronegativity of carbon compared to group 15 and 16 elements. Ligands, which are isoelectronic with amines and carbenes, but based on B, Al and Ga that are even less electronegative than C, will be extremely strong electron-donor ligands. Electrophilic stable carbenes will also be used for preparing stable organic radicals and polyradicals. An application, resulting from the stability of radicals, will be the discovery of efficient, non-toxic, hydrogen donors. Lastly iminato and ylide substituents, derived from the newly discovered non-electrophilic mesoionic carbenes, will be used for the preparation of strong neutral bases and hydride donors.
