The Chemistry of the Later 3d Metals with Terminal Chalcogenido, Imido, and Amido Ligands

University Of Kansas Center For Research Inc, Lawrence KS

Investigators

Abstract

This award in the Inorganic, Bioinorganic and Organometallic Chemistry program supports Professor Andrew S. Borovik at the University of Kansas to develop the chemistry of later 3d metals (Group 7 and beyond) with terminal chalcogenido (S, Se, Te), amido, and imido ligands. Complexes with these ligands have been proposed as key intermediaries in a variety of chemical processes. A bio-inspired approach will be used to isolate these complexes, in which control of the secondary coordination sphere is accomplished using structural principles found in the active sites of metalloproteins. Modular multidentate ligands have been designed and prepared to create rigid organic frameworks around coordinated metal ions. These ligands position hydrogen bond (H-bond) donating groups proximal to metal centers, forming specific microenvironments that assist in stabilizing the metal chalcogenido, amido or imido units. Particular emphasis will be placed on regulatory effects that the H-bonds have on reactivity. Long-term goals of this research include developing structure-function relationships for atom- and group-transfer reactions. The systems outlined in this proposal offer an approach to designing new bio-inspired metal complexes that have H-bond donors contained within rigid organic frameworks. The control of the molecular components that define the structure around the metal ion(s) permits the development of systems whose activity can be tailored to a particular reaction, and ultimately, a class of substrates. The ability to fine-tune the molecular design of the external ligand-binding site by varying the size and the nature of H-bonding groups is beneficial for constructing microenvironments about reactive species. This allows for the systematic study of structure-function relationships that can lead to a fundamental understanding of chemical processes and potentially useful systems for a variety of applications. Ultimately, this chemistry will provide insights into the properties of biological catalysts and will lead to new classes of synthetic catalysts that incorporate the exquisite control of reactivity characteristic of metalloenzymes. The proposed work will also increase our understanding of how noncovalent interactions in the secondary coordination sphere affect the chemical properties of transition metal complexes. The long-term goal of developing catalysts for reactions involving atom- and group-transfer would impact many aspects of synthetic and industrial chemistry. The research offers students and postdoctoral associates broad training in chemistry. In addition, the knowledge gained concerning how non-covalent interactions influence chemical properties can be applied to all aspects of chemical and material science.