Experimental and Computational Studies on the Mechanism of Transition-Metal-Catalyzed Oxidation and Halogenation Processes

细菌邻苯二酚双加氧酶是一种负责将羟基化的芳香族化合物转化为非环化合物的酶，因此在芳香族化合物的降解过程中起着核心作用。这些非血红素铁和类似的铜酶催化芳香族C-C键的氧化裂解，根据反应性C-C键相对于邻苯二酚底物羟基的位置，可分为传统和外部裂解邻苯二酚双加氧酶。我们将以含二联吡啶型配体和腐植酸衍生物的小分子模型化合物为基础，深入分析其反应机理和产物分布。此外，有机底物通过相同的催化体系转移到卤代化合物，这些反应也将得到详细的研究。这些研究将包括动力学实验、标记研究、活性中间体的捕获及其在低温下的完整光谱表征，以及计算工作，以推导出反应的相关势能面，并计算感兴趣的中间态的光谱性质。双联吡啶模型体系在分子基础上的详细机理信息将被用来模拟没有支撑双联吡啶配体的铁配合物的反应活性，这些结果将与DFG研究组内其他基团的类似研究进行比较。

Bacterial catechol dioxygenases are enzymes responsible for the conversion of hydroxylated aromatic into acyclic compounds and therefore play a central role within the degradation of aromatic compounds. These nonheme iron and similar copper enzymes catalyze the oxidative cleavage of aromatic C-C bonds and, depending on the position of the reactive C-C bond with respect to the hydroxyl groups of the catechol substrate, are classified into intradiol- and extradiol-cleaving catechol dioxygenases. Based on low molecular weight model compounds with bispidine-type ligands and with humic acid derivatives, we will thoroughly analyze the reaction mechanisms and product distributions. Moreover, organic substrates are transferred by the same catalyst systems to halogenated compounds, and these reactions will also be studied in detail. These studies will involve kinetic experiments, labeling studies, the trapping of reactive intermediates and their full spectroscopic characterization at low temperature and computational work to derive the relevant potential energy surfaces of the reactions and to compute the spectroscopic properties of interesting intermediate states. The detailed mechanistic information on a molecular basis of bispidine model systems will be used to model the reactivities of iron complexes without supporting bispidine ligands, and these results will be compared with similar studies of other groups within the DFG Research Group.