This SGER award in the Inorganic, Bioinorganic and Organometallic Chemistry Program supports research by Professor Christopher Cummins at MIT to pursue new methods of forming P-P triple bonds and incorporating phosphorous into organic molecules. This research builds upon a recently developed new synthesis of niobaziridine hydride systems that permits activation of the elemental P4 molecule leading to niobium-phosphorus triple bonds. This paves new pathways for P-atom transfer to main-group acceptors, such as niobium-mediated synthesis of PCR (phosphaalkyne) triple bonds. This research extends the niobium-mediated phosphorus-triplebond-forming chemistry to the element phosphorus itself, so as to form the P2 molecule under mild conditions of temperature and pressure and in homogeneous solution. Through mechanistic and computational studies of the P2 generation and trapping experiments, it is proposed to determine if the free diatomic P2 molecule is indeed an intermediate, as the chemistry may be explicable in terms of a P2 synthetic equivalent valuable for the synthesis of molecules containing embedded P2 units. It is also proposed to generate a W(CO)5 protected variant that retains the triple bond reactivity of free P2 but is longer lived, more efficiently trapped by unsaturated organic molecules, and available at room temperature. The studies of triple-bond generating reactions will be extended to include the target diatomic molecules, PAs and PN, which, like P2, are simple triple bond systems with no presently known solution chemistry.
This research will have an impact on the synthesis of phosphorus-containing organic molecules useful as ligands, in catalysis, or as pharmacophores. The propensity of the PP triple bond to serve as an aggressive double dienophile should enable the construction of four P-C bonds and two fused ring systems in a single step, under mild conditions. Undergraduate, graduate and postdoctoral students will be trained through interactions within the Cummins' research group, other groups at MIT, and other national and international collaborators.
