CAS: Can 1st Row Transition Metals Express the Covalency Typifying 2nd and 3rd Row Transition Metals: Comparative Studies

CAS：第一行过渡金属能否表达代表第二行和第三行过渡金属的共价：比较研究

• 批准号: 2348673
• 负责人: Peter Wolczanski
• 金额: $ 57.5万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-08-01 至 2027-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2348673&HistoricalAwards=false
• 关键词: CAS; 1st; Row; Transition; Metals

With the support of the Chemical Synthesis Program of the Chemistry Division, Professor Peter T. Wolczanski and his research team at Cornell University will investigate whether 1st row transition metals can be induced to express covalency typical of 2nd and 3rd row metals. Most commodity and fine chemicals are synthesized utilizing catalytic chemistry, with 2nd row transition metals being used to catalyze bond formations to carbon most commonly. Many of these metals are in low abundance and expensive; so-called precious metals. This research is directed at developing more sustainable alternative chemistries; namely by establishing ways of utilizing more abundant metals that are modified by ligands to provide the chemical reactivity necessary to supplant the current catalysts. Transformative ligands that expand the scope of applications via unique reactivity are a cornerstone of the program. A number of approaches involving different metal-ligand binding modes, and different electronic capabilities are expected to allow for the effective modulation of catalyst reactivity. One specific application is the synthesis of simple coordination complexes to enable light-initiated processes to occur more sustainably and with greater facility. An internet program/website will be established to provide a forum for Q&A for the community, and to serve as a news interface with the general public. The project will train graduate and undergraduate students in the fields of inorganic and organometallic chemistry in the synthesis and reactivity of transition metal compounds. As an ancillary effort an oral history organometallic chemistry will be assembled and made accessible through the internet.The coordination of strong field and redox non-innocent (RNI) ligands will be utilized with the goal of expanding the redox capability of targeted 1st transition series metals. The goal is the development of catalytic properties of these metals that are typical of 2nd and 3rd row metals. As strong fields impart covalency, bidentate pyrimidine-based chelates featuring anionic or neutral M-C bonds will be employed as inductively withdrawing ligands. As these complexes are predicted to have low-lying pi-antibonding orbitals and corresponding low-lying charge-transfer (CT) excited states, the complexes have potential applications as photoactive materials in photocatalysis. Reversible C-C bond breaking will be employed in low coordinate complexes to restrict RNI to 2e- changes. Chromium tetradentate chelates manifest chemistry that provides proof of this concept. New chelates with sterically/electronically protected components will hamper degradation and stabilize ligand platforms that will enable CH activation through transient imide/nitrene complexation. Non-ancillary ligands based on benzimidazole diamides will be used to reversibly mask alkylidenes that are capable of ring-opening metathesis polymerization and olefin metathesis. Using this ligand system, a reversible cycle involving a net methylene/dihydrogen metathesis will be realized. Additional fundamental information will be gleaned from comparisons of Cr vs Mo or W, Ti vs Zr, or V vs Nb, where comparative chemistry (metalaradical vs concerted) will elicit interpretations based on covalency.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.

在化学部化学合成项目的支持下，康奈尔大学的 Peter T. Wolczanski 教授和他的研究团队将研究是否可以诱导第一排过渡金属表达第二排和第三排金属的典型共价键。大多数商品和精细化学品都是利用催化化学合成的，其中第二行过渡金属最常用于催化与碳的键形成。其中许多金属储量低且价格昂贵。所谓的贵金属。这项研究旨在开发更可持续的替代化学物质；即通过建立利用更丰富的金属的方法，这些金属经过配体修饰，以提供取代当前催化剂所需的化学反应性。通过独特的反应性扩大应用范围的变革性配体是该计划的基石。许多涉及不同金属-配体结合模式和不同电子能力的方法有望有效调节催化剂反应性。一种具体的应用是合成简单的配位络合物，以使光引发的过程更可持续、更方便地发生。将建立一个互联网程序/网站，为社区提供问答论坛，并作为与公众的新闻界面。该项目将培训无机和有机金属化学领域的研究生和本科生过渡金属化合物的合成和反应性。作为辅助工作，口述历史有机金属化学将被组装并通过互联网提供。将利用强场和氧化还原非无辜（RNI）配体的协调，以扩大目标第一过渡系列金属的氧化还原能力。目标是开发这些金属的第二排和第三排金属的典型催化性能。由于强场赋予共价性，具有阴离子或中性M-C键的二齿嘧啶螯合物将被用作感应吸引配体。由于这些配合物预计具有低位π反键轨道和相应的低位电荷转移（CT）激发态，因此这些配合物作为光催化中的光活性材料具有潜在的应用前景。在低配位配合物中将采用可逆的 C-C 键断裂，以将 RNI 限制为 2e- 变化。四齿铬螯合物的化学反应证明了这一概念。具有空间/电子保护成分的新型螯合物将阻碍降解并稳定配体平台，从而通过瞬时酰亚胺/氮烯络合实现 CH 活化。基于苯并咪唑二酰胺的非辅助配体将用于可逆地掩蔽能够进行开环复分解聚合和烯烃复分解的亚烷基。使用该配体系统，将实现涉及净亚甲基/二氢复分解的可逆循环。其他基本信息将从 Cr 与 Mo 或 W、Ti 与 Zr 或 V 与 Nb 的比较中收集，其中比较化学（金属基与协同）将引出基于共价键的解释。该奖项反映了 NSF 的法定使命，并被认为是有价值的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来获得支持。