Electronic structure-chemical property relationship of binuclear 3d-metal structures.

本研究旨在从一种新型的适应性二硫酸盐配体出发，研究镍和铁的配位化合物的电子结构与化学性质之间的关系。硫和后过渡金属之间的化学键具有许多有趣的性质，其中之一是相对较高的共价性。较高的共价性有利于金属硫键上金属中心的电子耦合，这解释了自然界中各种金属硫结构的性质和功能。与天然结构不同，合成结构中金属位置之间的电子耦合通常非常强，其变化基本上是不可能的。为了克服这一限制，本研究项目解决了允许以系统方式改变双金属金属-硫结构中电子耦合强度的参数。对镍的双金属结构的初步研究表明，减弱电子耦合强度为提高这些化合物的氧化裂氢性能提供了合适的手段。同样的镍双金属化合物也为定量研究硫桥双金属结构的(分解)机制提供了高保真模型，而硫桥双金属结构在自然界中具有如此突出的特征。本研究项目的所有前人和未来的工作都依赖于一种新型的配体骨架的性质，该骨架结合了芳香族π-体系和硫酚基团的自适应和动态配位性质。这使得这些配体能够结合单个和多个金属原子，并灵活地适应金属氧化态的变化，这使得这些化合物显然适合本研究项目的目标--定量机理工作。从长远来看，这一研究项目的目标是开发具有反应性的3D金属结构，以高效的方式催化电子和化学键能量的相互转换。

This research project aims at studying the relation between the electronic structure and the chemical properties of coordination compounds of nickel and iron from a novel type of adaptive dithiolate ligands. The chemical bond between sulphur and a late transition metal features a variety of intriguing properties, one of which is a comparatively high covalent character. A higher covalent character is beneficial for electronic coupling of metal sites across metal-sulphur linkages, which explains the properties and function of a variety of metal-sulfur structures in Nature. Different from natural structures, the electronic coupling between metal sites in synthetic structures typically is very strong and its variation is essentially not possible. To overcome this limitation, this research project addresses parameters that allow for varying the strength of electronic coupling in bimetallic metal-sulphur structures in a systematic fashion. Preliminary work on bimetallic structures of nickel showed that attenuating electronic coupling strength provides suitable means to increase the performance of these compounds in oxidative hydrogen splitting. The same bimetallic compounds of nickel also provided high-fidelity models for quantitative studies of the mechanism of (dis)assembly of sulfur bridged bimetallic structures that feature so prominently in Nature. All precedent and future work of this research project relies on the properties of a novel type of ligand framework, which combines the adaptive and dynamic coordination properties of aromatic π-systems and thiophenol groups. This has allowed these ligands to bind a single and multiple metal atoms and adopt flexibly to changes in metal oxidation states, which renders these compounds clearly suitable for the quantitative mechanistic work that is the objective of this research project. On the long run, this research project aims for developing reactive 3d-metal structures that catalyze the interconversion of electrical and chemical bond energies in an efficient manner.