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

美国国家科学基金会化学部的化学催化计划支持弗吉尼亚大学的T.Brent Gunnoe教授研究金属介导的C-H活化。碳氢化合物的低温和选择性官能化仍然是石化工业中最重要的合成挑战之一。这项拟议的研究的最终目标是将C-H键的1，2-加成纳入M？X键(X=NR2，OR等)。转化为碳氢化合物功能化的催化循环。C-H键的活化策略包括通过金属中心配位C-H键，然后金属介导的质子从碳氢单元转移到杂原子配体，如氢氧化物或氨基。尽管最近有这种反应的例子，包括Ru(II)氢氧化物、Ir(III)烷氧基和Rh(I)芳氧基配合物激活C-H，但关于1，2-CH-跨越后过渡金属M-X键的加成反应知之甚少。这在一定程度上是由于已研究的系统数量有限。所提出的化学将通过制备新的d6和d8过渡金属氨基、氢氧化物、醇盐和相关的络合物，探索这些络合物激活烃的C-H键的能力，并最终探索芳烃和烷烃C-H活化的机理和选择性，来描述1，2-CH跨M-X键的加成反应的基本方面。机理研究将与北德克萨斯大学的Thomas Cundari教授和Brigham Young大学的Daniel Ess教授的理论小组合作进行。碳氢化合物的选择性官能化对商品化学部门、精细化学合成和化石燃料作为能源的有效利用非常重要。随着全球能源需求的增加给化石资源带来压力，更有效地将碳氢化合物转化为更高价值的材料变得越来越重要。例如，用于碳氢化合物部分氧化的选择性和高效催化剂可以简化能源密集型过程，并为化学工业提供范式转变。然而，如果不解决催化领域的重大基本挑战，特别是C-H活化和官能化反应，这些目标将无法实现。此外，拟议的研究将产生长期影响，培训合成和催化领域的未来化学家，这对全球化学工业的竞争力至关重要。

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.