Mechanisms of Homogeneous Activation of Hydrocarbons by Transition Metal Complexes

过渡金属配合物均相活化烃的机理

• 批准号: 8705228
• 负责人: Thomas Flood
• 金额: $ 30.29万
• 依托单位: University of Southern California
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-08-01 至 1991-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8705228&HistoricalAwards=false
• 关键词: Mechanisms; Homogeneous; Activation; Hydrocarbons; Transition

Metal compounds are used extensively as catalysts for facilitating structural conversions of hydrocarbons, as required for reforming petroleum distillates to produce high octane gasoline, and for the formation of carbon-carbon bonds, as is necessary in the utilization of coal for the synthesis of useful organic compounds. The goal of this project is to provide a more thorough understanding of such catalytic processes, with a focus on transition metal catalysis of the formation or cleavage of carbon-carbon or carbon-hydrogen chemical bonds. Mechanistic studies of reactions of hydrocarbons in the coordination sphere of soluble complexes of transition metals will be undertaken. The target systems have been chosen to provide well-defined examples of reactions which form or break C-H and C-C bonds. Reversible alkene insertions into metal carbon bonds, intramolecular gamma-C-H activations, and intermolecular C-H activations provide the focus for the work. Metal oxidation state, steric bulk and electronic effects of ancillary ligands, alkyl group structure, charge and chelate ring size will be investigated as variables in a detailed look at the mechanisms of representative reactions. Systems to be studiesd include complexes of Pt, Pd, Ti and Zr containing a deuterium-labeled 2,2-dimethyl-5-pentyl ligand which shows reversible alkene insertion by specific deuterium site exchange. Gamma-C-H activation will be investigated with a variety of deuterium-labeled square-planar iridium(I) alkyl complexes. Intra- and intermolecular C-H activation will be studied in a series of octahedral Os(II) and Ir(III) phosphine and phosphite alkyl hydride complexes. The possibility of dictating a preference for intermolecular activation of alkanes by the synthesis of cyclometallation-resistant ligands will be investigated. In all cases a thorough examination of mechanisms will be made using kinetics, deuterium site labeling, kinetic isotope effects, and the effect of substrate structure on reactivity.

金属化合物被广泛用作催化剂，以促进碳氢化合物的结构转化，这是重整石油馏分以生产高辛烷值汽油所必需的，也是形成碳-碳键所必需的，这是利用煤炭合成有用有机化合物所必需的。该项目的目标是更彻底地了解这种催化过程，重点是过渡金属对碳-碳或碳-氢化学键的形成或断裂的催化作用。将对过渡金属可溶络合物配位球内碳氢化合物的反应进行机理研究。目标系统被选择来提供形成或断裂C-H和C-C键的反应的明确例子。可逆烯烃插入金属碳键、分子内伽马-C-H活化和分子间C-H活化是本工作的重点。金属氧化态、辅助配体的空间体积和电子效应、烷基结构、电荷和螯合环的大小将作为变量进行详细研究，以了解典型反应的机理。将要研究的体系包括含有2，2-二甲基-5-戊基-2，2-二甲基-5-戊基配体的铂、钯、钛和锆络合物，该配体通过特定的氢中心交换显示可逆地插入烯烃。伽马-C-H活化将用不同的氚标记的方形平面Ir(I)烷基络合物来研究。我们将研究一系列八面体Os(II)和Ir(III)膦酸烷基氢化物的分子内和分子间的C-H活化。通过合成抗环金属化的配体来决定烷烃分子间活化的偏好的可能性将被调查。在所有情况下，都将使用动力学、氚位置标记、动力学同位素效应和底物结构对反应性的影响来彻底检查机理。