Catalytic Nitrene Reactions Enabled By Dinuclear Nickel Catalysts
Nitrenes are reactive intermediates that are known to generate high interest organic molecules. Due to their inherent instability, nitrenes are often stabilized by introducing them to transition metal complexes. Many transition metal stabilized nitrenes (M=NR2) have been reported and some of these complexes have been shown to control nitrene reactivity and selectivity. Transition metal nitrene reactivity can be categorized into two main groups: bond-insertion and group transfer reactions. In the reference to the former, chapter one of this dissertation highlights using unique dinuclear Ni catalysts to generate nitrenes from aromatic azides. These Ni2 nitrenes are used towards selective C(sp2)−H bond amination in order to generate indole and carbazole derivatives. This work highlights the unique properties of the Ni2 imide that enable a 1,2-addition pathway, which contrasts known bimetallic nitrene insertion reactions. A detailed mechanistic study, primarily using density functional theory (DFT) is the focus of this chapter.
Chapter two of this dissertation focuses on nitrene group transfer. In particular, this chapter highlights the ability of the dinuclear Ni catalyst [i-PrNDI]Ni2(C6H6) to react with aromatic azides to perform N=N coupling. A large scope of functional groups are tolerated in high yield with short reaction times. Catalyst comparison studies, studies on relevant catalytic intermediates for N=N coupling and reaction kinetics are shown in this chapter. Lastly, chapter three showcases the expansion of the nitrene group transfer ability of [i-PrNDI]Ni2(C6H6) to generate high molecular weight azopolymers from aromatic diazides. These azopolymers are generated from monomers often used in organic semi-conducting materials. End group control and post polymer functionalization are highlighted in this chapter. Lastly, this work showcases a new polymer, polyazoisoindigo, as the first organic semiconducting material that reversibly transitions from a colored to colorless state upon reduction.