CAREER: Probing Catalytic O-O Bond Formation with Psuedo-Tetrahedral Terminal Oxo Complexes

芝加哥大学化学系的John Anderson教授在化学系化学催化项目资助下，研究了水中析氧的催化作用。大多数可再生能源计划的核心是氢燃料的利用。生产氢燃料最简单的环保方法是将水催化分解为氢和氧。该过程的氧气形成部分被认为是最具挑战性的转变，以促进。众所周知，在催化过程中，两个氧原子必须结合并结合在一起才能形成氧气，但这种结合形成的确切机制目前尚不清楚，这限制了更有效催化剂的开发。安德森教授正在合成和研究含有过渡金属原子的化合物的催化活性，以便为析氧催化提供新的设计原则。在实验室之外，安德森教授正在与芝加哥南部社区的学校合作。他正在帮助学生们为科学博览会和全市范围的科学竞赛做准备，并为当地高中生创造了一个暑期实习机会，为他们提供“动手”的科学实验室体验。这些努力的目的是加强对通常服务不足的学生群体的科学教育，并鼓励他们对STEM领域的职业感兴趣。在这个项目中，安德森教授正在研究过渡金属系统析氧催化中氧-氧键形成的自由基耦合机制的细节和范围。这种机制假说最近得到了越来越多的支持，但对氧配体上自由基性质的程度或自由基性质在氧-氧键形成中的作用的研究很少。低坐标伪四面体复合体几何结构将允许合成金属-氧化合物，金属-氧多键特性部分稳定。这些物质被认为是催化析氧的中间体，这种几何形状有望产生可能与催化有关的不寻常的自旋态和电子结构。在合成之后，这些配合物通过各种技术，如EPR光谱、ENDOR光谱和各种x射线实验和光谱，被表征以确定在氧配体上的自旋离域程度。彻底的表征使详细的结构-功能研究成为可能。这些配合物参与氧-氧键形成催化的相对可行性，特别是关于它们的氧中心自旋密度，将为当前的机制假设提供信息，并为析氧催化提供新的设计原则。

In this project funded by the Chemical Catalysis Program of the Chemistry Division, Professor John Anderson of the Department of Chemistry at the University of Chicago is studying the catalysis of oxygen evolution from water. At the center of most renewable energy schemes is the utilization of hydrogen fuel. The simplest environmentally benign approach to the production of hydrogen fuel involves the catalytic splitting of water into hydrogen and oxygen. The oxygen-forming portion of this process has been considered the most challenging transformation to promote. While it is known that two oxygen atoms must combine and bond together during catalysis to form oxygen, the precise mechanism through which this bond formation occurs is currently unknown, limiting the development of more efficient catalysts. Professor Anderson is synthesizing and studying the catalytic activities of compounds that contain transition metal atoms in order to provide a new design principle for oxygen evolution catalysis. Outside of the laboratory, Professor Anderson is engaging in collaborations with schools in Chicago's south side neighborhoods. He is helping students to prepare for science fairs and city-wide science competitions, and has created a summer internship for local high-school students to provide them with a "hands-on" science laboratory experience. The aim of these efforts is to enhance the science education of a typically underserved group of students and to encourage their interest in careers in STEM fields.In this project, Professor Anderson is investigating the details and scope of a radical coupling mechanism for oxygen-oxygen bond formation in oxygen evolution catalysis by transition metal systems. This mechanistic hypothesis has recently gained increased favor, but there has been little investigation into either the degree of radical character on oxo ligands or the agency of radical character in oxygen-oxygen bond formation. A low-coordinate pseudo-tetrahedral complex geometry will allow for the synthesis of metal-oxo compounds that are partially stabilized by metal-oxygen multiple bond character. These species are proposed intermediates in catalytic oxygen evolution, and this geometry is expected to engender unusual spin states and electronic structures that may be relevant for catalysis. Following their synthesis, these complexes are being characterized to determine the degree of spin delocalization onto the oxo ligand via a variety of techniques such as EPR spectroscopy, ENDOR spectroscopy, and various X-ray experiments and spectroscopies. Thorough characterization is enabling detailed structure-function studies. The relative viability of these complexes to engage in oxygen-oxygen bond forming catalysis, particularly with regards to their oxygen-centered spin density, will both inform current mechanistic hypotheses and provide a new design principle for oxygen evolution catalysis.