Carbon is the building material upon which the elements of life (DNA, RNA, etc.) are constructed. Carbon generally forms four chemical bonds. In this project funded by the Chemical Synthesis Program of the Chemistry Division, Professor Guy Bertrand of the Chemistry and Biochemistry Department at the University of California – San Diego (UCSD), seeks to prepare compounds that violate the four-bond rule. The isolation of such new carbon species has been impeded by the belief that they are inherently unstable. Professor Bertrand’s laboratory has recently developed new methods to prepare compounds called carbenes, which contain only two bonds to carbon. These methods are extended to carbynes, compounds in which carbon contains only a one bond. The availability of these species leads to better understanding of how chemical reactions of carbon take place, which then permits control of the reactivity of carbon-containing species. Ultimately, this research may help in the advanced manufacturing of chemicals and materials as researchers may develop more selective approaches to synthesis (fewer by-products). The Professor Bertran's laboratory collaborates with the French Le Centre National de la Recherche Scientifique (CNRS). The exchange of undergraduates and graduates between UCSD and CNRS-associated universities enables the students to develop an international perspective on chemical production and workforce development.
The idea that monocoordinated carbon species may be isolable followed the discovery of amino substituents that mitigated the intrinsic tendency of carbenes to undergo dimerization and other reactions. Building on this idea, monocoordinated aminocarbanions (R2NC), aminocarbynes (R2NC), aminocarbocations (R2NC+), which feature six, five and four valence electrons, respectively, are prepared. Due to the importance of low coordinate main group compounds, aminophosphinidenes (R2NP) and aminoborylenes (R2NB), which are isoelectronic with the monocoordinated aminocarbanions and aminocarbocations, respectively, are synthesized. Some of the targeted species are non-isolable. Nonetheless, the pursuit of these high risk, high reward leads to new methodologies for in situ generated analogues. The fact that carbenes can simultaneously form two sigma bonds and monocoordinated compounds may form three opens a new model of chemical reactivity.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
