Getting a Grip on Reactive Metals

Dr. Laura Turculet, Assistant Professor of Chemistry, and the members of her research group refer to themselves first and foremost as synthetic chemists – that is, they are in the business of making molecules.

We encounter the products of chemical synthesis, the art of producing new substances from known compounds, frequently in everyday life. Modern society relies heavily on these substances, ranging from pharmaceuticals to modern materials such as plastics. As the target molecules become more and more complex, their syntheses become much more challenging. To overcome the many obstacles that stand in the way of the effective and economic production of desirable new compounds, chemists have long relied on the help of catalysts. A catalyst is a substance that is able to speed up a chemical reaction without itself being consumed in the process. Although various chemical and biochemical compounds can function as catalysts, transition metal-based catalysts have proven to be among the most versatile, efficient, and selective.

Given the current emphasis on sustainability, energy efficiency and effective use of natural resources (including petroleum-derived hydrocarbons), Laura sees great opportunities for the development of new types of highly reactive metal catalysts. In particular, she seeks to improve the efficiency of existing processes or gain access to brand new, less wasteful synthetic procedures. In her quest to develop better catalysts, Laura and her group dissect the transition metal catalyst into its component parts – the reactive metal and the groups bound to the metal, otherwise known as the ancillary ligands. Although these ancillary ligands are not directly involved in the bond-making and bond-breaking steps of the catalytic reaction, they are very important in influencing the properties of the reactive metal center.

Laura and her graduate students are engaged in the design and synthesis of ancillary ligands that she anticipates will endow the resulting transition metal complexes with specific properties, properties that she anticipates will lead to new reactivity and increased catalytic activity. She is specifically targeting a new family of ancillary ligands commonly referred to as “pincers”. These molecular pincers are specifically designed to grab the reactive metal center tightly, binding via three sites in order to create the optimum environment for the desired chemical reactivity. In one of their more significant achievements to date, Laura and her students have succeeded in developing iridium complexes, supported by silicon-containing pincer ligands, that are capable of breaking the strong C-H bonds in hydrocarbons under very mild conditions; an important step in the development of synthetic strategies that will make more efficient use of increasingly limited hydrocarbon resources.

Laura's group is funded by Dalhousie University, the Natural Sciences and Engineering Research Council (NSERC) of Canada, the Canadian Foundation for Innovation, and the Nova Scotia Research and Innovation Trust. Funding from the latter two agencies (New Opportunities Award) has enabled the installation of a new state-of-the-art laboratory for inorganic synthesis that houses her research program.