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Cohesion in Coordination Chemistry

配位化学中的内聚力

基本信息

批准号：
258769765
负责人：
Professor Dr. Stefan Grimme
金额：
--
依托单位：
Mulliken Center for Theoretical Chemistry
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2014
资助国家：
德国
起止时间：
2013-12-31 至 2017-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/258769765?language=en
关键词：
Cohesion Coordination Chemistry

项目摘要

This collaborative work addresses the issues of cohesion in coordination and organometallic chemistry fostered by a mutual effort in experimental and theoretical investigations of the role of predominantly non-covalent interactions (NCIs) in reactions involving d-block transition metals where intramolecular London dispersion forces are suspected to be essential to their stabilization. For years, NCIs have been overlooked in coordination chemistry. Recent research shows that accounting for the effect of these interactions was essential to produce a physically correct assessment of the importance of metals ligand retinue on association energies and on relative stabilities of intermediates. It is expected that in coordination reactions involving ligand-metal bond formation, as encountered in catalytic processes, remote organic fragments contribute to the ligand-metal association energy by way of a significant dispersion term. Recent advances in dispersion-corrected DFT (namely DFT-D3) renders the investigation of reactions involving large (100-200 atoms) transition metal complexes possible in the gas, solution, and the solid state. This constitutes a new framework for improving further the general understanding of reaction kinetic profiles, regio, chemo and stereoselectivities. However, two pitfalls remain. The first one is the lack of comprehensive accurate thermodynamic data for ligand-metal binding that could serve as standard for the evaluation of quantum chemical (QC) methods. The second, intimately bound to the improvement of the former, is rooted in the known limitations of continuum-based solvation models. The project proposes a solution based on the investigation of elementary reactions by means of isotherm titration calorimetry, a technique that allows the accurate measure of enthalpies of reactions as low as 1 kcal/mol. It targets the study of known transition metal reactions. Acquisition of thermodynamic information by ITC is to be confronted to the assessment of the same thermochemistry by theoretical methods based on DFT-D3 and coupled-cluster type wave function theory (WFT) in order to elaborate a new benchmark reference. The critical goal of this confrontation of theory with experiment is to evaluate on a systematic basis the performance of contemporary QC methods particularly for reactions occurring in solution. Further research will be focused on the joint experimental/theoretical assessment of the nature and strength of non-covalent interactions involved in so-called hemichelation by a systematic investigation of the thermochemistry of ligand interaction with hemichelates. Further research will target the synthesis of new cases of hemichelates bearing different electron-unsaturated metal centers.

这项合作工作解决了配位和有机金属化学中的内聚问题，这些问题是通过对主要非共价相互作用（nci）在涉及d-嵌段过渡金属的反应中的作用的实验和理论研究而促进的，其中分子内的伦敦分散力被怀疑是其稳定所必需的。多年来，NCIs在配位化学中一直被忽视。最近的研究表明，考虑这些相互作用的影响对于产生金属配体络合物对缔合能和中间体相对稳定性的重要性的物理正确评估至关重要。在涉及配体-金属键形成的配位反应中，正如在催化过程中遇到的那样，远程有机碎片通过一个重要的分散项对配体-金属缔合能做出贡献。弥散校正DFT（即DFT- d3）的最新进展使得研究气体、溶液和固态中涉及大型（100-200个原子）过渡金属配合物的反应成为可能。这为进一步提高对反应动力学分布、区域、化学和立体选择性的一般理解提供了一个新的框架。然而，仍然存在两个陷阱。一是缺乏全面准确的配金属结合热力学数据，无法作为评价量子化学方法的标准。第二个问题与前者的改进密切相关，其根源在于基于连续体的溶剂化模型的已知局限性。该项目提出了一种基于等温滴定量热法研究基本反应的解决方案，这种技术可以精确测量低至1千卡/摩尔的反应焓。它的目标是研究已知的过渡金属反应。将ITC获取的热力学信息与基于DFT-D3和耦合簇型波函数理论（WFT）的热化学评价理论方法相结合，形成新的基准参考。这种理论与实验对抗的关键目标是在系统的基础上评估当代质量控制方法的性能，特别是在溶液中发生的反应。进一步的研究将集中在通过系统地研究配体与半螯合物相互作用的热化学，对所谓半螯合作用中涉及的非共价相互作用的性质和强度进行实验/理论联合评估。进一步的研究将针对合成具有不同电子不饱和金属中心的半羧酸盐的新情况。