Low Oxidation State Complexes of Early Transition Metals with Aromatic Ligands

该奖项来自无机、生物无机和有机金属化学项目，为有机金属化学的一个项目提供了持续的支持，该项目的重点是过渡金属铬对芳烃的活化。碳氢化合物的活化在化学和制药工业中具有重要意义，因为碳氢化合物是合成大多数有机化合物的最终原料。该研究的总体目标是探索和开发早期过渡金属与芳香族配体的高度还原配合物的化学性质，特别是它们在温和条件下作为亲电芳烃取代新序列的中间体的潜力。这些实验建立在最近观察到的亲电试剂，如氯化苄或氢离子，很容易加入到苯三羰基的-4配合物中，得到类似于亲核加入到铬化合物中所得到的环己二烯配合物。该项目的具体目标包括：1)建立氯化苄氧化加成至-4-苯三溴二羰基的机理细节；2)探索将在-4-苯三溴三羰基配合物中添加活性芳烃的亲电官能团范围；3)确定各种取代芳烃的三羰基铬配合物的还原活化/亲电加成过程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激活序列的可能性，以及环戊二烯配体的还原激活的可行性。萘thalenide还原也将被用作用环戊二烯和pi-杂环配体取代早期过渡金属的羰基金属酸盐的途径。

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.