Dynamic Properties of Misdirected Ligand Complexes

俄克拉何马大学化学系的Michael T. Ashby博士在化学系无机、生物无机和有机金属项目的支持下，对含有几何约束的配体的金属配合物进行了研究，这些配体不能给金属提供π电子。因为它们的取向阻止它们利用最大数量的电子与金属成键，这些配体被称为“定向错误”。“该项目将解决以下基本问题：配体如何被‘误导’，但仍能牢固地附着在金属上；“误导”配体对过渡金属配合物基态和瞬态性质的影响配体“误导”和“重定向”的可能性可以有实际应用。为了解决这些问题，将利用配体合成一系列配合物，这些配体可以在允许π与金属相互作用的构象和“误导”的构象之间穿梭。将研究这些配合物的动态构象性质，并评估配体“误导”对配合物化学性质的影响。在实验室、工业和生物系统中进行的许多化学反应都有金属离子的参与。金属的独特反应性在很大程度上反映了反应过程中金属周围电子数量的变化。这个项目将探索如何设计复合物的基本问题，使附着在金属离子上的基团能够被迫提供可变数量的电子。将对系统进行研究，以确定如何获得这种化合物，以及控制金属电子计数的变化如何改变化学反应性。这将为理解现有流程和合理设计新流程奠定基础。

Dr. Michael T. Ashby, Department of Chemistry, University of Oklahoma, is supported by the Inorganic, Bioinorganic, and Organometallic Program of the Chemistry Division for a study of metal complexes containing ligands that are geometrically constrained so that they cannot donate pi electrons to the metal. Because their orientation precludes them from utilizing their maximum number of electrons in bonding with the metal, these ligands are termed `misdirected.` The project will address the fundamental questions of how can a ligand be `misdirected,` but still be firmly attached to a metal; the effects of `misdirected` ligands on the ground-state and transient properties of transition metal complexes; and the possibility that ligand `misdirection` and `redirection` can have practical application. To address these questions a series of complexes will be synthesized utilizing ligands that can be forced to shuttle between a conformation that allows pi interaction with the metal and one that is `misdirected.` The dynamic conformational properties of these complexes will be studied and the influence of ligand `misdirection` on the chemical properties of the complexes will be assessed. Many chemical reactions carried out in the laboratory, in industry, and by biological systems involve the participation of metal ions. Much of the unique reactivity of the metals is a reflection of variations, during the course of reactions, in the number of electrons surrounding the metal. This project will probe fundamental questions of how complexes can be designed so that groups attached to metal ions can be forced to provide variable numbers of electrons. Systems will be studied to determine both how to obtain such compounds and how controlled alterations in the metal electron counts can change chemical reactivity. This will set the ground work both to understand existing processes and to rationally design new ones.