Main Group and Transition Metal Complexes: From Fundamental Investigations to Photocatalysis

这项建议涉及化合物设计和催化剂开发的基本和应用方面。更具体地说，该提案提出了三个核心研究主题：探索非共价键与金属中心的相互作用；控制络合物中单一金属离子的各向异性的策略；以及增强稀土化合物的捕光能力，目标是改善光催化还原二氧化碳的能力。第一个主题集中在设计和组装分子支架的基本目标上，这些支架显示出金属阳离子和相关的Lewis碱之间的共价键程度非常低。这种非共价相互作用在分子、生物和聚合物科学的各个领域都是重要的。我们正在为无机化学中非共价相互作用的一个完全独特的方面做出贡献。在我们的工作之前，关于如何控制金属配体成键的基本问题并没有得到明确的认识。这些重要的基本相互作用在主族化学中的影响最近在我们贡献的文献中得到了赞赏。了解如何控制金属-配体的成键有助于深入了解影响金属阳离子Lewis酸度的方法，这将指导它们的化学方面，并挑战传统的金属-配体相互作用的成键描述。我们的策略基于选择具有受限几何特征的键合组，这些几何特征决定了它们的键合特征的对齐。我们进一步将这项工作扩展到能够激活一些小分子(例如二氧化碳、羰基、炔烃和氰键)的主族化合物。这一反应活性将是实现主族催化剂开发的重要一步。 我们第二个主题的基本动机是控制和规定过渡金属和f元素离子的电子各向异性。通过空间和电子调谐，我们将使络合物的物理、化学和磁性发生变化。一个目标是制造单离子钴和铁的络合物，其各向异性将显示为单独的分子磁体(所谓的“单分子磁体”)。我们的方法为我们提供了独特的机会来解决基于磁各向异性的预测，从而消除了通常在SMM合成工作中使用的一些意外。我们还预计，这将导致分子磁性构建块的设计。 应用于催化的几何和电子结构的控制是我们第三个核心主题背后的概念，它提供了Re(I)配合物的光化学和光物理性质和应用的重大变化。虽然这些特征已经被认识了一段时间，并且值得注意的是这些化合物具有出色的光催化还原二氧化碳的能力，但这一领域的发展一直受到常见的伪八面体FAC-[Rex(CO)3L2]化合物有限的结构和电子可变性的限制。我们将通过开发一种新的化合物来解决这些限制，该化合物具有新的RE中心的配位几何结构。这种新的结构极大地阐述了这一大类化合物的基本光物理特征，应该会产生更好的催化剂，以更低的能量发挥作用。更长远的目标是以Re(I)多金属网络为目标的新方法。我们还计划将这种化学扩展到可用作多相二氧化碳还原催化剂的新型多孔材料，以及研究当排列成有序阵列时Re中心的光物理特性的基本变化的变化。

This proposal addresses fundamental and applied aspects of compound design and catalyst development. More specifically, the proposal presents three core research themes: an exploration of noncovalent bonding interactions to metal centers; strategies to control anisotropy of single metal ions in complexes; and enhancing the light harvesting ability of Re compounds with the target of improved photocatalytic reduction of CO2. The first theme is centered on the fundamental objective to design and assemble molecular scaffolds that display an unusually low degree of covalent bonding between a metal cation and an associated Lewis base. Such noncovalent interactions is an important across diverse fields of molecular, biological and polymer science. We are contributing to a completely unique aspect of noncovalent interactions to inorganic chemistry. Prior to our work, the fundamental questions on how to control metal ligand bonding were not explicitly appreciated. The impact of these important fundamental interactions in main group chemistry has recently been appreciated in the literature to which we contributors. Understanding how to control metal-ligand bonding provides insights into methods to influence the Lewis acidity of metal cations, which directs aspects of their chemistry, and challenges conventional bonding descriptions of metal-ligand interactions. Our strategy is based on selecting bonding groups with restricted geometric features that dictate the alignment of their bonding features. We further extend this work to include main group compounds that are able to activate a number of small molecules (e.g. CO2, carbonyls, alkynes and nitrile bonds). This reactivity will be an important step forward in the realization of main group catalyst development. The fundamental motivation of our second theme is to control and dictate the electronic anisotropy of transition metal and f-element ions. Through steric and electronic tuning we will engender changes in physical, chemical, and magnetic properties of complexes. One objective is to produce single-ion cobalt and iron complexes whose anisotropies will reveal themselves as individual molecular magnets (so-called “single-molecule magnets”). Our approach provides us the unique opportunity to address the prediction of magnetic anisotropy based and thus remove some of the serendipity that is normally used in the synthetic work on SMMs. We also anticipate that this will lead to design of molecular magnetic building blocks. The control of geometric and electronic structure applied to catalysis are the concepts behind our third core theme which provides a major change to the photochemical and photophysical properties and applications of Re(I) complexes. While these features have been recognized since for some time and are noteworthy for the exceptional ability of these compounds to photocatalytically reduce CO2, the development of this field has been restricted by the limited structural and electronic variability of the common pseudo-octahedral fac-[ReX(CO)3L2] compounds. We will addresses these constraints by developing a new compounds that possess new coordination geometries for the Re centers. This new structure significantly elaboration of the basic photophysical features of this large class of compounds and should yield improved catalysts that would function with lower energy. Longer range objectives are targeting new approaches at Re(I) multimetallic networks. We also plan to expand this chemistry to novel porous materials that can function as heterogeneous CO2 ¬reduction catalysts as well as a means to study the changes to the fundamental changes to the photophysical features of the Re centers when arranged in ordered arrays.