Bonding and Reactivity in Low-Valent Dinickel Complexes

低价Dinickel络合物中的成键和反应活性镍化合物的一个显着特性是它们能够打破强化学键。事实上，一些蛋白质含有镍中心，可以与二氧化碳发生反应，二氧化碳具有非常强的键。镍基催化剂在与能源相关的化学领域有着广泛的应用。佐治亚理工学院的约瑟夫·P·萨迪吉教授领导的这项研究项目建立在紧密联系和能源相关性这些主题的基础上。该项目的重点是镍原子对。镍原子通过桥联原子或桥基成对连接。在这项工作中探索的连接物包括氢、非金属元素或其他金属。该项目研究了与每个镍中心结合较弱的桥接中心。这些异常的弱键应该使络合物足够稳定，可以被分离，但又足够不稳定，可以高度活性。对这些化合物的深入了解为设计打破强键的催化剂提供了洞察力。进行这项研究的研究生和本科生研究人员被介绍给成键和反应性的概念，以及一系列合成和光谱技术。该组织还参与了佐治亚理工学院的一个项目，该项目从科学领域代表性较低的人口中招募高中生。学生们被介绍通过一个夏天进行研究，然后通过学年进行研究。这种培训使学生为美国科学的未来做出贡献，成为教师，或作为学术、工业或政府实验室的研究人员。镍协会与现役或最近过渡的退伍军人有广泛的联系，并为那些重返全日制学习的人提供建议和鼓励。镍是金属-元素成键以及使催化成为可能的键断裂和成键反应的最近显著进展的主题。这项研究提出了两个镍(0)中心与Lewis酸相互作用形成桥联配体的结构。当Lewis酸是质子时，这种相互作用产生了一种罕见的线性氢化物桥；[Ni-H-Ni]核由一个三中心四电子键连接在一起，类似于双氟离子中的键。一个目标是合成一系列相关的氢化氢桥联镍络合物，从而能够评估桥联氢的氢化性质，并详细研究该络合物对氰化物的C-CN键的反应性。另一个目的是探索来自路易斯酸性主族物种的桥的形成，如碳阳离子、硼烷、丙烷或有机金属碎片。最后，在镍中心之间插入铜(I)或金(I)阳离子将提供跨三个金属中心具有单一网键的异金属体系。支持这些目的的假设是，[Ni-E-Ni]系综足够稳定，可用于分离或表征，但表现出不同于单镍络合物[Ni-E]、单独的镍或单独的桥联元素的反应活性。从事这个项目的学生学习键合和化学合成的概念。他们获得了制备对空气敏感的复合体的技术技能。他们接受了使用现代仪器进行分析的培训。这些研究人员包括研究生、本科生和高中生。该项目确定了对科学研究感兴趣的未被充分代表的少数民族学生。该培训为学生在教育、研究和工业领域的技术职业生涯做好准备。在另一种形式的外展中，Sadighi教授建议其他退伍军人重返全日制学习。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Bonding and Reactivity in Low-Valent Dinickel ComplexesA remarkable property of nickel compounds is their ability to break strong chemical bonds. Indeed, some proteins contain nickel centers that react with carbon dioxide, which has very strong bonds. Catalysts based on nickel are widely used in energy-related chemistry. The research project led by Professor Joseph P. Sadighi at the Georgia Institute of Technology builds on these themes of strong bonds and energy-relevance. The project focuses on pairs of nickel atoms. The nickel atoms are linked in pairs using bridging atoms or bridging groups. The linkers that are explored in this work include hydrogen, nonmetallic elements, or another metal. The project examines bridging centers that are weakly bonded to each nickel center. These unusually weak bonds should make the complexes sufficiently stable to be isolated, yet unstable enough to be highly reactive. A deeper understanding of these compounds is providing insights into the design of catalysts for breaking strong bonds. The graduate and undergraduate researchers who carry out this research are introduced to concepts of bonding and reactivity, and to an array of synthetic and spectroscopic techniques. The group also participates in a Georgia Tech program to recruit high school students from demographics underrepresented in science. The students are introduced to research through a summer and then through the academic year. This training prepares students to contribute to the future of science in the United States as teachers, or as researchers in academic, industrial, or government laboratories. The PI has extensive contacts with currently serving or recently transitioned veterans, and provides advice and encouragement to those returning to full-time study.Nickel has been the subject of remarkable recent advances in metal-element bonding, and in bond-breaking and bond-forming reactions that enable catalysis. This research presents architectures derived from the interaction of two nickel(0) centers with a Lewis acid to form a bridging ligand. When the Lewis acid is a proton, this interaction creates a rare linear hydride bridge; The [Ni---H---Ni]+ core is held together by a three-center, four-electron bond, analogous to that in the bifluoride ion. One aim is the synthesis of a series of related hydride-bridged dinickel complexes, enabling an assessment of the hydridic character of the bridging hydrogen, and a detailed study of the complex's reactivity toward the C-CN bonds of nitriles. Another aim explores the formation of bridges derived from Lewis-acidic main group species such as carbocations, boranes, alanes, or organometallic fragments. Finally, the insertion of copper(I) or gold(I) cations between the nickel centers would afford heterometallic systems with a single net bond across three metal centers. The hypothesis underpinning these aims is that the [Ni---E---Ni] ensembles are sufficiently stable for isolation or characterization, yet display reactivity distinct from that of mononickel complexes [Ni-E], nickel alone, or the bridging element alone. Students who work on this project learn concepts of bonding and chemical synthesis. They acquire technical skills in the preparation of air-sensitive complexes. They are trained in analysis using modern instrumentation. These researchers include graduate students, undergraduates, and high school students. The program identifies underrepresented minority students interested in scientific research. This training prepares students for technical careers in education, research, and industry. In another form of outreach, Professor Sadighi advises fellow veterans on their return to full-time study.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.