STUDIES ON THE STRUCTURE AND CATALYSIS OF NONHEMEIRON COMPLEXES WHICH FUNCTION ENZYME-LIKE CATALYTIC ACTIVITY

根据有机产物的产物分析和溶液中中间铁配合物的光谱，研究了非血红素铁双加氧酶和单加氧酶模型络合物的结构和功能。利用儿茶酚铁对单加氧酶模型反应进行关联。1.儿茶酚双加氧酶模型体系在催化反应活性的基础上，提出邻苯二酚形成儿茶酚铁(III)络合物，该络合物可能与半水杨酸铁(II)络合物作为与氧反应的直接中间体。光谱学已经表明儿茶酚铁(III)的形成，但没有得到半奎尼奥铁(II)的直接证据。在这项研究中，我们分离了儿茶酚铁(III)络合物。通过ESR、穆斯堡尔谱、EXAFS谱，特别是~1H和~2H核磁共振谱对配合物的结构进行了研究，结果表明，邻苯二酚配体具有较强的自由基性质，支持半喹基铁物种作为直接活性物种。单加氧酶模型体系我们开发了儿茶酚铁(III)络合物/对苯二酚/O2，用于在非水有机溶剂(如丙酮)中催化芳烃、环状和非环状饱和烃的单氧化反应。其中一个重要而有趣的结果是选择性很大程度上依赖于吡啶的浓度。在低浓度的吡啶中，主要以羟基化反应为主，而在吡啶浓度较低的情况下，主要以羰化反应为主。反应活性还取决于对苯二酚上的取代基。活性物种为铁-氧物种，而不是羟基自由基。

Structure and function of the model complex of nonheme iron dioxygenases and mono-oxygenases were studied on the bases of product analysis of organic products and spectroscopy of the intermediate iron complexes in the solution. Catecholdioxygenase model reaction was correlated by using catecholatoiron for monooxygenase model reaction.1.Catecholdioxygenase Model SystemOn the basis of the catalytic reactivity, we have proposed that the catechol forms catechotoiron(III) complexes which may be in equilibrium with semiquinonatoiron(II) complexes as direct intermediates for the reaction with oxygen. Spectroscopy has indicated the formation of the catecholatoiron(III), but no direct evidence for the semiquinonatoiron(II) has been obtained. In this study we have isolated catecholatoiron(III) complexes. Structure of the complexes in solution was studied spectroscopically, e.g. ESR, Mossbauer, EXAFS, specially by ^1H and ^2H NMR, and the strong radical character of the catecholate ligand , supporting the semiquinonateiron species as an direct active species, has been clearly shown.2. Monooxygenase Model SystemWe have developed the catecholoteiron(III) complex/hydroquinones/O2 for the catalytic monooxygenation of aromatics, cyclic and acyclic saturated hydrocarbons in nonaqueous organic solvent such as acetonitile. One of the important and interesting results is the great dependence of selectivity on the pyridine concentration. In the low pyridine concentration, hydroxylation is the main reaction, but in pyridine carbonylation is the main reaction. The reactivity also depends on the substituents on the hydroquinones. Active species was found to be iron-oxygen species rather than the hydroxyl radical.