Cohesion in Coordination Chemistry

这项合作工作解决了配位中的凝聚力和有机金属化学的问题，这是由实验和理论研究中的共同努力所促进的，该实验和理论研究主要是非共价相互作用(NCIS)在涉及d-嵌段过渡金属的反应中的作用，其中分子内的伦敦色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，考虑到这些相互作用的影响，对于从物理上正确地评估金属配位体对缔合能和中间体相对稳定性的重要性是必不可少的。预计在涉及配体-金属键形成的配位反应中，如催化过程中遇到的那样，远程有机碎片通过显著的色散项贡献配体-金属缔合能量。色散校正密度泛函理论(DFT-D3)的最新进展使得研究大(100-200个原子)过渡金属络合物在气体、溶液和固态中的反应成为可能。这构成了一个新的框架，进一步改善了对反应动力学曲线、区域、化学和立体选择性的一般理解。然而，仍然存在两个陷阱。第一个问题是缺乏全面、准确的配体-金属结合热力学数据来作为评价量子化学(QC)方法的标准。第二，与前者的改进密切相关，根植于基于连续介质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对元素反应进行研究的解决方案，这项技术允许准确测量低至1千卡/摩尔的反应热。它的目标是研究已知的过渡金属反应。ITC热力学信息的获取面临着基于DFT-D3和耦合簇型波函数理论(WFT)的理论方法对同一热化学的评价，以阐述一个新的基准参考。这种理论与实验对峙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，特别是对于溶液中发生的反应。进一步的研究将侧重于通过系统地研究配体与半螺旋体相互作用的热化学，对所谓的半螺旋作用中所涉及的非共价相互作用的性质和强度进行联合实验/理论评估。进一步的研究将着眼于合成具有不同电子不饱和金属中心的半螺旋化合物的新案例。

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.