CAS: Four-Coordinate Iron- and Cobalt-Carbene Complexes for Carbene-Transfer Catalysis

在化学系化学催化项目的支持下，西弗吉尼亚大学的Carsten Milsmann将研究基于地球上丰富的金属，特别是铁和钴的过渡金属催化剂。复杂有机分子的构建是开发新型药物、功能材料和消费品的重要目标。将结构单元如烯烃、芳烃和饱和烃加工成更复杂的结构可以通过涉及卡宾片段的化学反应来实现，这通常需要金属催化剂来有效地进行。目前可用的最佳催化剂系统严重依赖稀有和贵金属，这增加了所得产品的成本，并由于资源有限而带来了可持续性挑战。本研究的目的是开发地球丰富的金属配合物，可以取代贵金属在卡宾转移催化的设计原则。特别是铁和钴催化工艺的发展有可能改善美国的精细化学品生产。Milsmann博士和他的学生将积极参与社区外展活动，包括在K-12水平上开发和展示化学演示，并将为初中和高中学生开发新的动手实验。在化学系化学催化计划的支持下，西弗吉尼亚大学的卡斯滕·米尔斯曼将研究四配位铁和钴的电子结构，碳烯络合物及其作为碳烯转移催化中的胜任中间体的所得反应性。特别感兴趣的是具有正方形平面或顺式双空位八面体几何形状的配合物，其具有邻近类卡宾配体的开放配位位点。这些研究的第一个目的是建立在分子结构和配位几何形状的变化如何影响所得到的配合物和它们的反应性金属类卡宾片段的电子结构。第二个目标是通过研究催化活性，可分离的铁和钴-卡宾络合物，将电子结构的差异与反应性的变化联系起来。所提出的研究的一个关键假设是，在正方形平面卡宾配合物中的开放配位位点将允许前所未有的控制使用基板上的定向基团的卡宾转移的区域选择性。最后，第三个目标是研究四配位铁卡宾参与[2+2]环加成化学的潜力，这是铁催化剂介导的烯烃复分解的关键一步。所提出的配合物具有配位不饱和的金属中心，潜在地开辟了新的机会，控制反应性相比，以前报道的铁-卡宾配合物。这些研究将直接探讨最近的计算预测，已确定铁卡宾络合物与钳型配体作为烯烃复分解催化剂的有前途的候选人。该奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

With the support of the Chemical Catalysis program in the Division of Chemistry, Carsten Milsmann of West Virginia University will study transition metal catalysts based earth-abundant metals, specifically iron and cobalt. The construction of complex organic molecules is an important target in the development of novel pharmaceuticals, functional materials, and consumer products. The elaboration of building blocks such as olefins, aromatics, and saturated hydrocarbons into more complex structures can be achieved by chemical reactions involving carbene fragments, which typically require metal catalysts to proceed efficiently. The best catalyst systems available currently rely heavily on rare and precious metals, which increases the cost of the resulting products and presents sustainability challenges due to limited resource availability. This research aims to develop design principles for earth-abundant metal complexes that can replace precious metals in carbene transfer catalysis. The development of iron- and cobalt-catalyzed processes in particular has the potential to improve fine chemical production in the United States. Dr. Milsmann and his students will actively participate in community outreach involving the development and presentation of chemistry demonstrations at the K-12 level, and will develop new hands-on experiments for middle and high school students.With the support of the Chemical Catalysis program in the Division of Chemistry,Carsten Milsmann of West Virginia University will study the electronic structures of four-coordinate iron- and cobalt-carbene complexes and their resulting reactivities as competent intermediates in carbene transfer catalysis. Of particular interest are complexes with square-planar or cis-divacant octahedral geometries that possess open coordination sites adjacent to the carbenoid ligand. The first aim of these studies is to establish how changes in the molecular structure and coordination geometry influence the electronic structures of the resulting complexes and their reactive metal carbenoid fragments. The second aim seeks to connect differences in electronic structure to changes in reactivity by studying catalytically competent, isolable iron- and cobalt-carbene complexes. A key hypothesis of the proposed research is that open coordination sites in square-planar carbene complexes will allow unprecedented control over the regioselectivity of carbene transfer using directing groups on the substrates. Finally, the third aim is to investigate the potential of four-coordinate iron carbenes to engage in [2+2] cycloaddition chemistry, which is a key step toward iron catalyst-mediated olefin metathesis. The proposed complexes possess coordinatively unsaturated metal centers, potentially opening up new opportunities for the control of reactivity compared to previously reported iron-carbene complexes. These studies will directly probe recent computational predictions that have identified iron-carbene complexes with pincer-type ligands as promising candidates for olefin metathesis catalysis.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.