Stabilization of Unique Chemical Bonding Environments and Exploration of Small Molecule Reactivity

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As part of the ongoing research within my group, in this proposal we will be focusing on the following projects that span our areas of specialty including main group and transition metal synthetic chemistry. Building upon the experience and strengths in the Masuda Research Group, I propose to continue research and expand upon our knowledge in the following areas: 1. Hemilabile chelating ligands: metal complexes for exploration of small molecule reactivity and catalysis We will extend our investigation of the coordination chemistry our teraryl cyclopentadienyl ligands and explore the reactivity of the resulting metal complexes. The hemilability of this ligands results from the strongly bound anionic cyclopentadienyl group and the more weakly p-bound aryl group. I propose to continue with this project with more exciting targets including utilizing the potential redox properties of the hemilabile teraryl group to help stabilize low-oxidation state metal centers. These species can then be used as synthons for lower oxidation state metals. These will be tested for further reactivity with small molecules and in catalysis. Sterically bulky, bidentate ligands have proven to be very important in coordination chemistry of main group, transition, and f-block metals. Often, these bidentate ligands consist of donors such as imines, amines, phosphinimines, carbonyls, thiocarbonyls, alkoxides, and phosphine oxides. In the unsymmetrical systems, different donors may be used to exploit differences in the hardness and softness of the donor atoms. Ylides are well known in organic chemistry, particularly as Wittig reagents, and are used as soft, 2-electron donors in the area of coordination chemistry. There are few examples in the literature of ylides that contain the fluorenylidene group. We propose to prepare a variety of chelating ligands, where one side has an typical donor (N, O, S) and the other has the flexible, carbon-based ylide/fluorenylidene-phosphorane fragment. This ligand arrangement will either allow for the isolation of 6-membered metal chelates coordinated via the hard imine and the soft ylide fragment, or pseudo-6-membered chelates coordinated through the hard imine and the soft, 5-membered, 6-p electron portion of the aromatic fluorenyl anion. It is possible that there will be fluxionality between the two types of chelation and this fluxionality can be exploited to affect the reactivity of metal complexes. 2. Reactivity with small molecules with N-Heterocyclic carbenes and phosphinyl radicals For well over a decade, I have explored the reactivity of singlet carbenes and phosphinyl radicals with a wide variety of small molecules. These include systems with reactive E-E bonds, E-H bonds, and extended p-systems. I propose on targeting the reaction of singlet carbenes and phosphinyl radicals with a number of exotic small molecules/functional groups to form new functional groups with new and unexpected properties.