Low Oxidation State Complexes of Early Transition Metals with Aromatic Ligands

该奖项来自无机化学、生物无机化学和金属有机化学计划，为金属有机化学项目提供持续支持，该项目的重点是过渡金属铬对芳香烃的活化。碳氢化合物的活化在化工和制药工业中非常重要，因为碳氢化合物是合成大多数有机化合物的最终起始原料。本研究的总体目标是探索和发展早期过渡金属与芳香族配体的高度还原的配合物的化学，特别是它们在温和条件下作为一种新的亲电取代芳烃序列的中间体的潜力。这些实验建立在最近的观察结果的基础上，即亲电性物质，如氯化苄或氢离子，很容易与苯铬三甲酰基的ETA-4-络合物反应，得到类似于通过亲核加成得到的环己二烯络合物。该项目的具体目标包括：1)建立氯化苄基氧化加成到ETA-4-苯基铬三甲基二阴离子的机理细节，2)探索将添加到ETA-4-芳基铬三甲基二阴离子络合物中活化芳烃的亲电官能团的范围，以及3)测定各种取代芳烃的三甲基铬络合物的还原活化/亲电加成反应的范围和区域选择性。还将研究芳烃与其他金属/配体模板配位的还原活化序列的可能性，以及环戊二烯配体还原活化的可行性。异苯二甲酸二苯醚还原也将被用作取代具有环戊二烯和pi-杂环配体的早期过渡金属的羰基金属酸盐的一种途径。

This award from the Inorganic, Bioinorganic and Organometallic Chemistry Program provides continued support for a project in organometallic chemistry, the focus of which is the activation of aromatic hydrocarbons by the transition metal chromium. The activation of hydrocarbons is of great importance in the chemical and pharmaceutical industries, since hydrocarbons are the ultimate starting materials for the synthesis of most organic compounds. The overall objective of the research is to explore and develop the chemistry of highly reduced complexes of the early transition metals with aromatic ligands, particularly their potential as intermediates in a novel sequence for electrophilic arene substitution under mild conditions. These experiments build on the recent observation that electrophiles such as benzyl chloride or the hydrogen ion add readily to the eta-4-complex of benzenechromiumtricarbonyl, giving cyclohexadienyl complexes analogous to those prepared by nucleophilic addition to this chromium compound. Specific objectives of the project include 1) establishing the mechanistic details of the oxidative addition of benzyl chloride to the eta-4-benzenechromiumtricarbonyl dianion, 2) exploring the range of electrophilic functional groups which will add to the activated arenes in eta-4-arenechromiumtricarbonyl dianion complexes, and 3) determining the range and regioselectivity of reductive activation/electrophilic addition procedures with chromiumtricarbonyl complexes of a variety of substituted arenes. The possibility of reductive activation sequences with arenes coordinated to other metal/ligand templates will also be examined, as will the feasibliity of reductive activation of cyclopentadienyl ligands. Napthalenide reduction will be used also as a route to substituted carbonylmetalates of early transition metals with cyclopentadienyl and pi-heterocycle ligands.