John Riedesel

Date of Graduation

2016

Document Type

Thesis

Degree Type

MS

College

Eberly College of Arts and Sciences

Department

Chemistry

Committee Chair

Jessica Hoover

Committee Co-Chair

Carsten Milsmann

Committee Member

Brian Popp

Committee Member

Bjorn Soderberg

Abstract

Over the past 50 years, there has been an explosion in the progress of transition-metal mediated reaction design, allowing chemists to perform a vast array of organic and inorganic transformations. While first-row transition-metals play a role in many reactions that have been known for some time, second- and third-row transition-metals have been key for the discovery and success of many of the most well-known and utilized reactions in homogeneous catalysis existing today. However, developing reactions utilizing first-row transition-metals has re-gained in popularity over recent years, in part due to the general expense of heavier metals. Also, the ability of first-row transition-metals to perform unique transformations or tolerate different functional groups in substrates is often a motivation to explore their applications in synthetic reactions.;Inspiration for the design of many catalyst systems is often drawn from biological processes, namely enzyme catalysis. Various transition-metals are found within enzymes, being necessary for most of their functions. Enzymes are highly refined catalysts for performing reactions essential to life, which are often found to be difficult to accomplish synthetically. Among these is the nitrogenase enzyme, named for its primary biological function, the reduction of dinitrogen to ammonia. In addition to dinitrogen reduction, nitrogenases can perform reduction reactions on a wide range of small molecules. Of particular interest is the recently discovered ability of vanadium nitrogenase to perform the complete deoxygenative reductive coupling of carbon monoxide to form small-chain hydrocarbons, a reaction not yet accomplished in a homogeneous model system.;The unique ability of the vanadium nitrogenase variant to perform the reductive coupling of carbon monoxide provided an inspiration to develop new homogeneous vanadium systems capable of mimicking the reactivity observed with nitrogenase enzymes. Hydrazines were chosen to investigate in place of dinitrogen due to its weaker nitrogen-nitrogen bond. Isonitriles were chosen to investigate for reductive coupling reactions in place of carbon monoxide due to their ease of handling. Additionally, the coupling of isonitriles with bisnucleophiles was investigated using iron and cobalt sources as an alternative to palladium catalysts.

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