Biography
I am originally from Concord, North Carolina, and received my bachelor of science degree in chemistry from the University of North Carolina at Chapel Hill in 2009. As an undergrad, I worked for Dr. Royce Murray, synthesizing various ligands and metal complexes in preparation for electrochemical studies.
Research Projects
The ultimate goal of my project is to install a new type of non-innocent ligand on unsaturated metals thus creating a new type of unsaturated metal complexes to explore reactivity with small substrates like N2, CO, CO2,and H2.
1,2,4,5-s-tetrazines have been demonstrated as redox active ligands that can store up to 2 electrons. A new type of redox active ligand is the bis(tetrazinyl)pyridine ligand (bTzP) which incorporatestwo tetrazines.
Preliminary results of reaction of bTzP and Cu powder have shown the oxidation of Cu(0) powder to Cu(II) via Electron Paramagnetic Resonance Spectroscopy (EPR) indicating that the bTzP ligand can indeed oxidize metallic copper. The question that still remains is whether there are two ligands per Cu or only one?
Currently, the redox properties of this pincer ligand are being explored with Ni metal. Group 10 metals are known for their abilities to activate substrates in catalytic reactions. A motivation to study nickel catalysis chemistry is simply that nickel, in comparison to other metals in the same group (Ni, Pd, Pt), is cheaper and more abundant.
A synthetic route was explored via NiCl2·THF1.5and bTzP. The product crystallized in dichloromethane by slow diffusion of pentane to yield bright orange crystals with an empirical formula of Ni2(bTzP)2Cl4, which exists as a centrosymmetric chloride-bridged dimer as seen below.
Ni(bTzP)Cl2(MeCN), (shown below) can be synthesized by refluxing NiCl2·THF1.5and bTzP ligand in MeCN. The product was crystallized by slow evaporation in MeCN to yield bright orange crystals.
These two Ni species can then act as a platform from which we will make, by reaction with reducing agents, unsaturated Ni complexes with electrons stored in the bTzP ligand.
Biography
I am originally from Kansas City, MO, and I received my B.S. in chemistry at Truman State University in Kirksville, MO in 2009. As an undergrad I worked under Dr. James M. McCormick on oxidation of Ru and Cr complexes using ozone. I also worked with Dr. H. David Wohlers on the development of a tactile periodic table for use as an educational tool for the visually impaired.
Research Projects
A new class of potentially redox non-innocent ligands includes molecules containing both pyridyl and pyrrolide moieties. One such ligand is 2-pyridylpyrrolide.
Transition metal complexes containing these ligands have the potential to store electrons and then transfer them to substrates.
Addition of reducing equivalents to divalent iron, cobalt, nickel, and copper bis-pyridylpyrrolide complexes results metal-based reduction followed by ligand rearrangement!
Cyclic voltammetry shows two oxidative waves for NiL2.
However, upon addition of chemical oxidizing equivalents to either CuL2or NiL2complexes a ligand-based oxidation occurs, followed by further reactivity of the presumed radical species to form free protonated ligand and a secondary organic product. I am currently working on modification of the ligand to inhibit degradation of the radical cationic species.
Installation of only one ligand onto the metal center will result in a more unsaturated (reactive) species, so work is currently underway to synthesize three or four coordinate divalent metal complexes containing only one pyridylpyrrolide equivalent. For example:
In addition, a ligand containing one pyridyl and two pyrrolide moieties has been developed by Dr. Nobuyuki Komine (a). I am working to install this dianionic ligand onto divalent late transition metals to form neutral complexes whose redox properties will be investigated.
An analogous ligand containing one pyrrolide and two pyridyl moieties has been previously prepared, though application of redox non-innocent properties has yet to be investigated (b).
I am working to compare the redox properties of these two ligands, which can then be applied for use in chemical transformations.
