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

在这个由化学系化学催化计划资助的项目中，芝加哥大学化学系的约翰安德森教授正在研究从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。生产氢燃料的最简单的环保方法是将水催化分解为氢和氧。这一过程的氧气形成部分被认为是最具挑战性的转化促进。虽然已知两个氧原子在催化过程中必须联合收割机并键合在一起以形成氧，但是这种键形成的精确机制目前尚不清楚，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，以期为析氧催化提供新的设计原理。 在实验室外，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一个典型的服务不足的学生群体的科学教育，并鼓励他们在STEM领域的职业兴趣。在这个项目中，安德森教授正在研究的细节和范围的自由基耦合机制的氧-氧键的形成在氧析出催化过渡金属系统。这一机制假说最近获得了越来越多的青睐，但很少有调查的程度自由基性质的氧代配体或机构的自由基性质的氧-氧键的形成。 低配位准四面体络合物几何结构将允许合成通过金属-氧多重键特征部分稳定的金属-氧代化合物。这些物种是催化析氧的中间体，这种几何形状预计将产生不寻常的自旋状态和电子结构，可能与催化有关。在它们的合成之后，这些络合物被表征以通过各种技术如EPR光谱、ENDOR光谱和各种X射线实验和光谱来确定自旋离域到氧代配体上的程度。彻底的表征使详细的结构-功能研究成为可能。这些复合物参与氧-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，将告知当前的机理假设，并为析氧催化提供新的设计原理。

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.