Activation of Carbon-Hydrogen Bonds by Late Transition Metal Hydroxide and Amido Complexes

点击翻译按钮获取中文摘要

The Chemical Catalysis program in the Chemistry Division at the National Science Foundation supports Professor T. Brent Gunnoe of the University of Virginia for studies of metal-mediated C-H activation. The low temperature and selective functionalization of hydrocarbons remains one of the foremost synthetic challenges in the petrochemical industry. The proposed research is driven by the ultimate goal of incorporating the 1,2-addition of C-H bonds across M?X bonds (X = NR2, OR, etc.) into catalytic cycles for hydrocarbon functionalization. The strategy for C-H bond activation involves the coordination of C-H bonds by the metal center followed by metal-mediated transfer of a proton from the hydrocarbyl unit to a heteroatomic ligand such as hydroxide or amido. Despite recent examples of such reactions, including C-H activation by Ru(II) hydroxide, Ir(III) alkoxide and Rh(I) aryloxide complexes, little is known about 1,2-CH-addition across late transition metal M-X bonds. This is due, in part, to the limited number of systems that have been studied. The proposed chemistry will delineate fundamental aspects of 1,2-CH additions across M-X bonds by preparing new d6 and d8 transition metal amido, hydroxide, alkoxide and related complexes, exploring the ability of these complexes to activate C-H bonds of hydrocarbons, and ultimately probing the mechanism and selectivity of aromatic and alkane C-H activation. The mechanistic studies will be performed in collaboration with the theoretical groups of Professor Thomas Cundari (University of North Texas) and Professor Daniel Ess (Brigham Young University).The selective functionalization of hydrocarbons is important to the commodity chemical sector, fine chemical synthesis and the efficient utilization of fossil fuels as energy resources. With the increase in global energy demand placing a strain on fossil resources, more efficient conversion of hydrocarbons into higher value materials is increasingly important. For example, selective and efficient catalysts for the partial oxidation of hydrocarbons could streamline energy intensive processes and provide a paradigm shift for the chemical industry. However, such goals will not be achieved without addressing substantial fundamental challenges in the field of catalysis, especially C-H activation and functionalization reactions. In addition, the proposed research will have long term impact by training future chemists in the area of synthesis and catalysis, which is vital for competitiveness in the global chemical industry.