RUI: Extended Metal Atom Chain Complexes of Fe and Co Supported by a C3 Symmetric, Scaffolded Ligand Platform

在化学系化学合成项目的支持下，弗曼大学的加里吉耶和杰斐逊E。阿巴拉契亚州立大学的贝茨将研究含有三个金属原子（如铁和钴）的一维链的新化合物，其中金属原子由于它们的接近而彼此形成键。这项研究将产生新的分子，控制金属原子链周围的环境，从而影响金属-金属相互作用。 这些化合物将揭示金属原子如何相互作用，以及单个金属的性质（如磁性）是否可以预测控制。 为了实现这些目标，Guillet团队将设计和合成一系列新化合物，并由合作者Jefferson Bates进行计算建模。Guillet小组的学生将在实验室环境中获得实践培训，同时学习适当的化学安全，以及如何使用先进的仪器合成和表征化合物。在贝茨小组工作的学生将获得利用计算机预测新化合物的性质的经验，以及如何将这些预测与Guillet小组获得的实验测量值进行比较。在弗曼和阿巴拉契亚州立大学的本科研究经验往往是一个关键时刻，当学生真正了解什么是未来的科学，技术，工程和数学（STEM）领域的工作需要。来自Guillet和Bates小组的学生将获得他们感兴趣的领域的相关培训和经验，并将为未来从事化学科学做好更好的准备。铁和钴的新型扩展金属原子链（EMAC）配合物的开发对于理解金属的性质非常重要。金属键合在不同的配位几何形状和影响这些有趣的系统的物理性质的因素。 通过控制中心三金属核周围的配体框架，可以合理地设计具有由小的金属间距离促进的各种高自旋基态电子构型的EMAC。 过去的合成策略使用三个空间位阻桥联配体，如2，6-双（三甲基甲硅烷基氨基）吡啶，以包围和稳定三金属核。 然而，由于需要低配位数的环境来产生高自旋，因此合成广泛的高自旋三金属EMAC的努力受到缺乏分离的络合物的稳定性的阻碍。 该提议测试了这样的假设，即在结合所有供体原子的C3对称支架上构建的配体将能够更好地支持Fe和Co的三金属EMAC，并且这些络合物将具有增加的稳定性。 利用简单的胺化反应，2，6_二溴吡啶将被伯胺官能化，并在第二胺化反应中连接到骨架分子上。 锂化和transmetalloy步骤将形成铁和钴的三金属EMAC结合实验测量，这些金属-金属键的性质将通过使用密度泛函理论和多组态波函数理论的计算方法进行探索。 一个更稳定的EMAC的扩展库将有助于建立对多个直接金属-金属键和导致高自旋磁基态的因素的更多理解。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With the support of the Chemical Synthesis program in the Division of Chemistry, Gary Guillet of Furman University and Jefferson E. Bates of Appalachian State University will study new chemical compounds containing one dimensional chains of three metal atoms, such as iron and cobalt, where the metal atoms form bonds with each other due to their proximity. This study will produce new molecules that control the environment around the chain of metal atoms therefore influencing the metal-metal interactions. These compounds will shed light on how exactly metal atoms interact with each other and if the properties, such as the magnetism, of the individual metals can be predictably controlled. To accomplish these goals, the Guillet team will design and synthesize a series of new compounds supported with computational modeling performed by collaborator Jefferson Bates. Students in the Guillet group will gain hands-on training in a laboratory setting while learning proper chemical safety, and how to synthesize and characterize chemical compounds using advanced instrumentation. Students working in the Bates group will gain experience utilizing computers to predict the properties of new compounds and how to compare those predictions with the experimental measureables obtained in the Guillet group. The undergraduate research experience at both Furman and Appalachian State is often a crucial time when students truly get to know what a future working in a science, technology, engineering, and mathematics (STEM) field entails. The students from both the Guillet and Bates groups will gain pertinent training and experience for their fields of interest and are will be better prepared to pursue a future career in chemical sciences.The development of new extended metal atom chain (EMAC) complexes of iron and cobalt is important for understanding the nature of metal-metal bonding in varying coordination geometries and the factors that affect the physical properties of these interesting systems. By controlling the ligand framework around the central trimetallic core it may be possible to rationally design EMACs with various high-spin ground state electronic configurations facilitated by small intermetallic distances. Past synthetic strategies used three sterically encumbering bridging ligands, such as 2,6-bis(trimethylsilylamino)pyridine, to surround and stabilize the trimetallic core. However, efforts to synthesize a broad array of high spin trimetallic EMACs have been hampered by the lack of stability of the isolated complexes since low coordination number environments are needed to engender high spin. This proposal tests the hypothesis that ligands built upon a C3-symmetric scaffold that incorporates all the donor atoms will be better able to support trimetallic EMACs of Fe and Co and that these complexes will have increased stability. Utilizing simple amination reactions, 2,6-dibromopyridine will be functionalized with a primary amine and in a second amination reaction attached to a scaffolding molecule. Lithiation and transmetallation steps will form trimetallic EMACs of Fe and Co. In combination with experimental measurements, the nature of these metal-metal bonds will be explored through the use of computational methods from density functional theory and multiconfigurational wavefunction theories. An expanded library of more stable EMACs will help to build increased understanding of multiple direct metal-metal bonds and the factors that lead to high-spin magnetic ground states.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.