SusChEM: Development and Applications of Ligand Donor Parameters for High Valent Transition Metal Systems

密歇根州立大学的亚伦·奥多姆教授在化学系化学催化(CAT)计划的支持下，发现和开发了可持续、高氧化态、过渡金属基催化剂的配体给体参数(LDPs)。这些参数表达了给体配体如何与亲电金属中心相互作用，并加速开发未被开发、廉价、富含地球和非常活性的金属中心的催化剂的开发。正在开发的用于评价配体供体能力的系统涉及合成多功能的Ncr(N-i-Pr2)X家族的铬(VI)硝基(其中X是被评价的配体)。这项研究扩大了对结构中使用的有机金属配体的分析，并确定改变金属上的多个配体是否会导致可预测的变化。LDP方法被应用于钛催化的氢胺化反应，并作为其他高氧化态过渡金属催化剂的基准，用于钼基施罗克歧化反应和用于烯烃氢氨基烷基化反应的锆络合物。在钛催化剂的开发中，配体参数化法有望成为一种多组分、一锅法，用于生成各种重要的杂环体系，这些杂环体系通常用于医药等产品。钛是第二丰富的过渡金属，而且无毒，因此这种类型的高效催化剂的开发提供了化学上有趣和可持续的机会。此外，还探讨了基于铬的参数化在钼和锆基催化剂中的适用性--这些催化剂也是富含稀土的非贵金属催化剂，具有可持续和环境友好的特点。参与这项研究的研究生、本科生和博士后助理在化学催化和合成方面接受了优秀的培训，适合在学术机构、政府实验室或行业工作。配体给体参数的开发可能适用于许多类型的高价催化剂，从而通过建立新的可持续催化剂系统的预测能力而影响更大的科学界。

Professor Aaron L. Odom of Michigan State University is supported by the Chemical Catalysis (CAT) Program in the Division of Chemistry to discover and develop Ligand Donor Parameters (LDPs) for sustainable, high oxidation state, transition-metal based catalysts. These parameters express how the donor ligands interact with the electrophilic metal centers and expedite catalyst development with underexplored, inexpensive, earth-abundant, and very reactive metal centers. The system being developed for the evaluation of ligand donor ability involves synthetically versatile chromium(VI) nitridos of the family NCr(N-i-Pr2)X (where X is the ligand under evaluation). This research expands the analysis of organometallic ligands used in the structure and determines if changing multiple ligands on the metal leads to predictable changes. The LDP method is applied to titanium-catalyzed hydroamination reactions and, as a benchmark for other high oxidation state transition metal catalysts, to molybdenum-based Schrock metathesis reactions and zirconium complexes used in hydroaminoalkylation reactions of olefins. As applied to titanium catalyst development, the ligand parameterization shows promise as a multi-component, one-pot method for the generation of a variety of important heterocyclic systems commonly employed in products like pharmaceuticals. Titanium is the second most abundant transition metal and is non-toxic, so that the development of efficient catalysts of this type offers chemically interesting and sustainable opportunities. In addition, the applicability of the chromium-based parameterization is explored in molybdenum- and zirconium-based catalysts - these are also earth-abundant, non-precious metal catalysts that are sustainable and environmentally-friendly. Graduate and undergraduate students and postdoctoral associates involved in this research receive excellent training in chemical catalysis and synthesis appropriate to employment in academics, government laboratories, or industry. The development of ligand donor parameters may be generalizable to many types of high valent catalysts thus impacting the greater scientific community by establishing predictive capabilities for new sustainable catalyst systems.