With the support of the Organic Dynamics Program in the Chemistry Division, Professor Guy Bertrand of the Chemistry Department at the University of California - Riverside, will study four different classes of compounds, the isolation of which have been impeded by the belief that they are inherently unstable, or have eluded the synthetic skills of investigators. They are non-heteroatom substituted cyclopropenylidenes (hydrocarbon carbenes) and their dimers (triafulvalenes), larger ring size carbocycliccarbenes that benefit from aromaticity, and bent-allenes. These species have not only been chosen because they represent exciting synthetic challenges but more importantly because they should feature interesting electronic and steric properties, which can lead to important applications, especially as ligands for transition metal catalysts. Over the years the success of homogeneous catalysis can be attributed largely to the development of a diverse range of ligand frameworks that have been used to tune the behavior of the various systems. The ultimate goal of this effort is to provide the catalytic community with new, readily available ligands, which will allow for the development of truly practical catalysts that will find application in both academia and industry.
Additionally, this project is at the interface between physical, organic and organometallic chemistry and is therefore well suited to the education of scientists at all levels. It is of paramount importance for the future to find catalysts able to transform abundant and cheap molecules into useful compounds ranging from bulk chemicals to therapeutics. The University of California- Riverside, classified as a minority serving institution, is well positioned to provide the highest quality educational experience for students underrepresented in science. Because of this fact, a diverse group of students will be involved in the project. This research will also promote collaborative research and the exchange of undergraduates, graduates and postdoctoral fellows between UC Riverside and several French universities.
Our research deals with environmentally friendly catalytic methods, which have obvious environmental impact since they permit waste reduction. Efficient and selective preparation of organic molecules is critical for mankind. Many of the most proficient known processes depend on the availability of catalysts, and it is of paramount importance for the future to find catalysts able to transform abundant and cheap molecules into useful compounds ranging from bulk chemicals to therapeutics. Over the years the success of transition metal catalysis can be attributed largely to the development of a diverse range of ligand frameworks that have been used to tune the behavior of the various systems. Recently, major advances have been reported thanks to the use of electron-rich phosphines and cyclic diaminocarbenes. During this funding period, we have uncovered several novel families of stable carbenes, and related carbon-based ligands such as cyclopropenylidenes, bent-allenes and mesoionic carbenes, which behave as even more electron-donating ligands. Because of the peculiar electronic and steric properties of these species, the corresponding metal complexes are very robust and should find applications in both industry and academia. We have also reported that these novel carbenes can act as catalysts on their own rights (without metals) and can activate small molecules and strong bonds. As an example, we found that carbenes can activate elemental phosphorus, which opens the way for the preparation of phosphorus derivatives without using chlorine. It is an important step to meet the growing demand in phosphorus derivatives and the increasingly stringent environmental regulations. The University of California at Riverside is recognized as Hispanic Serving Institution (HIS), and has a large undergraduate minority population. All undergraduate students, who have been involved in this project, decided to attend a graduate school to prepare a PhD in chemistry. Our laboratory is a joint venture between the University of California and the CNRS (French National Center for Scientific Research), and our NSF supported work has favored many exchanges between the US and Europe.
