SusChEM: Tools for the Development of High-Valent Transition Metal Catalysts

在这个由美国国家科学基金会化学部化学催化计划资助的项目中，密歇根州立大学的亚伦·奥多姆教授和他的同事们正在开发一种新的方法来预测如何提高化学反应的速度，以降低能源消耗，并对大规模化学生产提供更具体的控制。奥多姆集团正在探索多组分偶联催化，以此作为一种手段，以更高的产率减少获得更复杂的化学产品所需的时间和能量。他们的方法侧重于使用钛和锆等早期过渡金属，这些金属富含地球，提供独特的化学产品。通过了解和系统化控制这些催化剂的反应活性的因素，最大限度地减少了催化剂优化所需的时间和精力。催化剂的优化在系统中进行了探索，这些系统显示了一种多组分、一锅法生产各种不同的重要杂环核心的前景，该方法通常用于制药。研究生和本科生参与研究，学习无机/有机金属化学和化学实验的原理。配体的参数化方法依赖于容易合成的铬(VI)硝基配合物，其中估计的围绕铬中心旋转的势垒是通过氨基氮孤对和供体配体的供体(sigma和pi)竞争金属上的受体轨道来衡量供体能力的。在核磁共振氢谱中用自旋饱和转移测量的新参数被称为配体给体参数(LDP)。在初步研究中，配体描述符LDP已被应用于钛催化的炔烃与伯胺的氢胺化反应。辅助配体对钛催化性能的影响可以用电子元器件的LDP和空间描述符的埋藏体积百分比来有效地模拟。该方法允许在催化剂合成之前预测反应速率，识别发生副反应或催化剂降解的体系，在某些情况下，还可以确定催化中间体。在这个研究项目中，参数正在扩展到新的配体类型。涉及更多不同配体类型的催化建模的其他方法也在探索中。

In this project funded by the Chemical Catalysis Program of the Chemistry Division of the National Science Foundation, Professor Aaron Odom and coworkers at Michigan State University are developing a new method to predict how the rates of chemical reactions can be enhanced to lower energy consumption and provide more specific control of large scale chemical production. The Odom group is exploring multicomponent coupling catalysis as a means of lowering the time and energy required to access more complex chemical products in greater yield. Their method focuses on the use of early transition metals like titanium and zirconium, which are earth-abundant and offer unique chemical products. By understanding and systematizing the factors that control the reactivity of these catalysts, the time and effort required for catalyst optimization is minimized. Catalyst optimization is explored in systems that show promise for a multicomponent, one-pot method of generating a variety of different important heterocyclic cores commonly employed in pharmaceuticals. Graduate and undergraduate students participate in the research, learning the principles of inorganic/organometallic chemistry and chemical experimentation. The method for ligand parameterization relies on readily synthesized chromium(VI) nitrido complexes, where the estimated enthalpic barrier to rotation around the chromium center serves as a measure of donor ability through competition for acceptor orbitals on the metal between the amido nitrogen lone pair and donation (sigma and pi) from the donor ligand. The new parameter measured by spin saturation transfer in the 1H NMR spectra has been dubbed the Ligand Donor Parameter (LDP). In preliminary studies, the ligand descriptor LDP has been applied to titanium-catalyzed hydroamination of alkynes with primary amines. The effect of the ancillary ligands on the titanium catalysis can be effectively modeled using LDP for the electronic component and percent buried volume for the steric descriptor. The method allows the prediction of reaction rates prior to catalyst synthesis, the identification of systems that undergo side reactions or catalyst degradation, and, in some cases, the determination of catalytic intermediates. In this research project, the parameters are being expanded to new ligand types. Additional methods of modeling catalysis involving more diverse ligand types are also being explored.