Polynuclear Clusters in Biology - Structure, Reactivity

生物体内各种底物的氧化和还原对维持生命的过程至关重要。多电子转移过程，虽然在自然界中不太频繁，但同样重要。其中包括：氮气在氮酶中6e还原为氨，亚硫酸盐在亚硫酸盐还原酶中6e还原为硫化物，亚硝酸盐在亚硫酸盐还原酶中6e还原为氨，以及光合作用中2H20氧化为O2。本文主要研究了a)参与多电子还原的金属酶和b)在氧化过程中具有活性的非卟啉、非fe /S、铁中心的合成类似物。具体来说，Fe/M/S （M=Mo，V）的合成、结构、光谱性质和反应性。Fe/M/S簇有望作为含钒或铁代替钼的氮酶和替代氮酶中Fe/M/S中心的合成类似物。将合成的新型Fe/S簇作为氮化酶P簇的模型。将合成含有π受体配体的Fe/S簇的超分子组装体。，以及它们在双金属活化和催化还原二氮中的可能作用。多核、混合配体、羧酸-儿茶酚酸第一行元素配合物将作为催化各种底物多电子氧化的酶活性位点的结构和反应性模型进行研究。儿茶酚酸配体在这些化合物中的功能，作为氧化等价物的储存位点，将被确定。

The oxidation and reduction of various substrates in living organisms are of fundamental importance to life sustaining processes. Multi-electron transfer processes, although less frequent in nature are of equally great importance. Included among the latter are: the 6e-reduction of N2 to ammonia in nitrogenase, the 6e-reduction of sulfite to sulfide and of nitrite to ammonia in sulfite and nitrite reductases respective And the 4e- oxidation of 2H20 to O2 in photosynthesis. This proposal is concerned with the synthesis and study of synthetic analogs for a) metalloenzymes involved in multi-electron reduction and b) the non-porphyrin, non-Fe/S, iron centers active in oxidation processes. Specifically,: the synthesis, structures, spectroscopic properties and reactivitys of Fe/M/S (M=Mo,V) proposal. The Fe/M/S clusters are expected to sere as synthetic analogs for the Fe/M/S centers in the nitrogenases and alternate nitrogenases that contain vanadium or iron in place of molybdenum. The new types of Fe/S clusters that will be synthesized are designed as models for the P- clusters of nitrogenase. Superamolecular assemblies with attended Fe/S clusters containing pi acceptor ligands will be synthesized., and their possible function in the bimetallic activation and catalytic reduction of dinitrogen will be investigated. Multi-nuclear, mixed-ligand, carboxylate-catecholate complexes of first row elements will be studied as structure and reactivity models for the active sites in enzymes that catalyze the multi-electron oxidation of various substrates. The function of the catecholate ligands in these compounds, as storage sites of oxidizing equivalents, will be determined.