Tuning of Metal-Centered Radicals for Substrate Activations and Catalysis

这项由美国国家科学基金会化学部化学催化计划颁发的奖项支持坦普尔大学的Bradford Wayland博士的研究，他致力于研究选择性还原一氧化碳和二氧化碳并将其转化为有用的有机材料的新型催化剂。这些化学变化可以用来解决能源研究中的重大当代问题。这项研究包括寻找基于富含地球的第一过渡系列金属络合物的催化剂。研究目标的实现将推动对经济、液体燃料和化学原料生产的长期稳定至关重要的化学技术领域的发展。参与这项研究的学生在化学合成和表征以及化学催化方面都得到了很好的培训。研究的核心目标是利用含有金属中心自由基的双金属络合物来完成具有热力学挑战的一氧化碳和二氧化碳的转化。金属络合物的选择以热化学准则和密度泛函理论计算为指导。在温和的条件下获得有效的催化中间体的能力是由配体调节的，这些配体旨在以最小的金属-金属键支持双金属配合物。席夫碱大环配体是一种易于制备的、低成本的卟啉替代品。非大环四齿配体为迁移插入提供了途径，而这些路径在与大环配体的络合物中被抑制。设计了一系列具有吡咯和亚胺给体的阴离子三齿钳形配体，以形成以金属为中心的自由基，其中金属具有d7或d9电子构型。Pd(I)和Pt(I)的衍生物为扩大目前二氧化碳活化反应的极限提供了最好的机会。Ni(I)和Fe(I)的络合物是利用富含稀土的第一过渡金属实现碳氧化物催化转化的主要候选者。

This award by the Chemical Catalysis Program in the NSF Division of Chemistry supports the research of Dr. Bradford Wayland of Temple University, who pursues new classes of catalysts for the selective reduction and conversion of carbon monoxide and carbon dioxide into useful organic materials. These chemical transformations can be used to solve major contemporary issues in energy research. The research includes the pursuit of catalysts based on earth-abundant, first transition series metal complexes. Realization of the objectives of the research will advance areas of chemical technology important for long term stability in the production of economical, liquid fuels and chemical feed stocks. The students involved in this research receive excellent training in chemical synthesis and characterization, and chemical catalysis.The core objective of the research is to utilize bimetallic complexes containing metal-centered radicals to accomplish thermodynamically challenging transformations of carbon monoxide and dioxide. The selection of the metal complexes is guided by thermochemical criteria and DFT computations. The ability to attain productive intermediates for catalysis in mild conditions is tuned by the ligands, which are designed to support bimetallic complexes with minimal metal-metal bonding. Schiff base macrocyclic ligands are being developed as easily prepared, low-cost substitutes for porphyrins. Non-macrocyclic tetradentate ligands provide pathways for migratory insertions that are inhibited in complexes with macrocyclic ligands. A series of anionic tridentate pincer type ligands with pyrrole and imine donors are designed to form metal-centered radicals in which the metal has a d7 or d9 electron configuration. The Pd(I) and Pt(I) derivatives afford the best opportunities to expand the current limits of carbon dioxide activation reactions. The complexes of Ni(I) and Fe(I) are leading candidates to accomplish catalytic conversion of carbon oxides using earth abundant first transition metals.