Spectroscopic and Theoretical Elucidation of Oxygen-Activating Transition Metal Centers – Developing Magnetic Raman Spectroscopy as a new Experimental Method

含铁系统是目前FOR 5215研究计划的核心重要性，具有大量具有挑战性的光谱和电子结构问题。铁中心在一次翻转过程中可以以多达四种不同的氧化态存在，每一种氧化态都可以与多种自旋态相关联。此外，高自旋和低自旋表面之间的变化在这样的系统中是相当常见的（两态反应性）。即使是最强大的量子化学方法，从理论上预测这些态的几何和电子结构仍然是非常具有挑战性的。先进的光谱学和最先进的量子化学的精心组合是确定这些系统的催化机制的最佳方法。因此，光谱学可以提供的任何信息都是至关重要的。本项目的主要目标是（）。建立磁（共振）拉曼光谱法作为过渡金属化学中的新型光谱工具，以及ii.）探索FOR 5215计划内科学合作产生的最有趣的催化活性铁络合物的分子和电子结构。对于本提案的第一部分，我们将建立一个专用的磁共振拉曼装置，开发迄今为止未知的理论，为这种方法，提供简单，易于理解的系统的基准结果，并最终将这种方法应用于FOR 5215研究计划所追求的问题。对于本提案的第二部分，我们将联合收割机结合我们部门现有的大量光谱方法（穆斯堡尔，EPR，CD/MCD，UV/维斯，共振拉曼，SQUID）与ORCA电子结构包中包含的强大量子化学机械，以研究FOR 5215内部的选定系统和反应机制。

The iron-containing systems that are of central importance for the present FOR5215 research initiative feature a large array of challenging spectroscopic and electronic structure problems. The iron centers can exist in up four different oxidation states over the course of a single turnover, each of which can be associated with a variety of spin states. Also, changes between high-spin and low-spin surfaces are rather common in such systems (two-state reactivity). Predicting the geometric and electronic structures of these states theoretical is still highly challenging, even for the most powerful quantum chemical methods. A careful combination of advanced spectroscopy and state-of-the-art quantum chemistry is the best way forward in determining the catalytic mechanisms of these systems. Thus, any information that spectroscopy can provide is of paramount importance. Our main goals for this project are i.) to establish a magnetic (resonance) Raman spectrometry as a novel spectroscopic tool in transition metal chemistry, and ii.) to explore the molecular and electronic structures of most interesting catalytically active iron complexes arising from scientific collaboration within the FOR5215 initiative. For the first part of this proposal, we will build a dedicated magnetic resonance Raman setup, develop the so far unknown theory for this method, provide benchmark results on simple, well-understood systems and finally apply this methodology to the problems pursued by the FOR5215 research initiative. For the second part of this proposal, we will combine the substantial array of spectroscopic methods available in our department (Mössbauer, EPR, CD/MCD, UV/vis, resonance Raman, SQUID) with the powerful quantum chemical machinery contained in the ORCA electronic structure package to study selected systems and reactions mechanisms inside FOR5215.