Dynamic Ligands for Sustainable Molecular Catalysis

用于可持续分子催化的动态配体

• 批准号: RGPIN-2014-05926
• 负责人: Blacquiere, Johanna
• 金额: $ 2.55万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=645579
• 关键词: Dynamic; Ligands; Sustainable; Molecular; Catalysis

The research program, 'Dynamic Ligands for Sustainable Molecular Catalysis', targets innovative catalysts for the synthesis of high-value organic compounds. Advances in catalyst development will be achieved by expanding the fundamental design parameters and principles of cooperative ligands. Transition-metal complexes of these ligands will be exploited in catalytic processes that are highly atom-economic and that use non-toxic and abundant feedstocks (i.e. water, oxygen and first-row metals). Specifically, we target allylic oxidation and hydration reactions. The new catalytic systems will be powerful in applications of organic synthesis in both the academic and industrial realms. **Catalysts structures exploit cooperative characteristics, where reactivity at the metal centre is amplified or modulated by a secondary process or functionality. These synergistic relationships include ligands that demonstrate responsive hapticity (dynamic coordination) or second-coordination sphere processes. The latter includes functionalities that participate in hydrogen-bonding or intramolecular proton transfer. These cooperative relationships open new pathways for reactivity or selectivity that are inaccessible through traditional activation of substrates with transition metals. A main objective of this work is to gain a molecular-level understanding of these processes and how they are altered with changes in ligand design. This insight is crucial to the development of high-performance catalysts. **The research program is divided between three main research branches.* *1) Dynamic Mixed-Donor Ligands for Late-Metal Complexes. We are developing a new ligand family P-AzA that is comprised of a neutral phosphine and an anionic 1-azaallyl fragment. The ligand has the potential to bind to metals in a variety of modes and this coordination shift in response conditions of the system (i.e. introduction of other ancillary ligands or reagents). A thorough understanding of these systems is attained through detailed spectroscopic and reactivity studies, the results of which are necessary for the development of catalytic systems. Catalytic testing of this unique ligand framework is expected to uncover unprecedented activity and selectivity.**2) Selective Oxidation Mediated by Bifunctional Nickel Complexes. Dioxygen is an ideal oxidant and O-atom source as it is highly abundant and, if properly controlled, generates environmentally benign by-products. Control is a major challenge, which can be achieved with uniquely designed metal complexes. We target nickel-NHC complexes that contain hydrogen-bond donors adjacent, but not attached, to the metal centre (NHC = N-heterocyclic carbene). We postulate that these secondary interactions will alter reactivity, diverting away from deactivated or decomposed products. Reactivity studies will provide the groundwork for the development of aerobic oxidation catalysts.**3) High-Performance Catalysts for the Anti-Markovnikov Hydration of Alkynes. Conversion of alkynes to aldehydes with environmentally benign water is 100% atom-economic. Catalytic systems are needed that operate at lower catalyst loadings, lower temperatures and at faster rates. Proton transfer is a key step in the catalytic cycle and is dramatically assisted by ligands that promote intramolecular movement. An extremely promising, but underexploited system is the PR2NR'2 ligand family. Catalytic and stoichiometric studies of several variants (R/R' = Ph, Ar, Cy, Bn, tBu) will uncover the optimal phosphine donor strength and amine basicity for promoting rapid and selective product formation.

该研究计划“用于可持续分子催化的动态配体”，旨在创新催化剂，用于合成高价值有机化合物。通过扩大合作配体的基本设计参数和原理，将实现催化剂开发的进步。这些配体的过渡金属复合物将在高度原子经济且使用无毒和丰富的原料（即水，氧气和第一行金属）的催化过程中利用。具体而言，我们靶向烯丙基氧化和水合反应。新的催化系统将在学术和工业领域的有机合成应用中具有强大的作用。 **催化剂结构利用合作特征，其中金属中心的反应性被次要过程或功能放大或调节。这些协同关系包括表现出响应性触觉（动态协调）或第二配位球过程的配体。后者包括参与氢键或分子内质子转移的功能。这些合作关系为反应性或选择性开辟了新的途径，这些途径是通过传统的具有过渡金属的基板激活而无法访问的。这项工作的一个主要目的是获得对这些过程的分子级别的理解，以及如何随着配体设计的变化而改变它们。这种见解对于高性能催化剂的发展至关重要。 **研究计划分为三个主要的研究分支。**1）晚期金属复合物的动态混合配体。我们正在开发一种新的配体p-aza，该家族由中性磷酸和阴离子1-氮杂片段组成。配体有可能与多种模式中的金属结合，并且在系统响应条件下的这种配位转移（即引入其他辅助配体或试剂）。通过详细的光谱和反应性研究，对这些系统进行了彻底的了解，其结果对于开发催化系统是必需的。这种独特的配体框架的催化测试有望发现前所未有的活性和选择性。** 2）由双功能镍复合物介导的选择性氧化。二恶英是理想的氧化剂和O-ATOM源，因为它高度丰富，如果得到了适当的控制，则会产生环境良性的副产品。控制是一个主要的挑战，可以通过设计独特的金属配合物来实现。我们靶向含有氢键供体的镍-NHC络合物（NHC = n-beterocyclic Carbene）。我们假设这些二次相互作用将改变反应性，从而从停用或分解的产品中转移。反应性研究将为有氧氧化催化剂的发展提供基础。用环境良性水将炔烃转化为醛是100％原子经济学。需要在较低的催化剂负载，较低的温度和更快的速度下运行催化系统。质子转移是催化循环中的关键步骤，并由促进分子内运动的配体极大地帮助。 PR2NR'2配体系列是一个极其有希望的，但不受欢迎的系统。多种变体（R/R'= PH，AR，CY，BN，TBU）的催化和化学计量研究将发现最佳的磷酸供体强度和胺基碱性，以促进快速和选择性的产物形成。