HIGH OXIDATION STATE TUNGSTEN AND MOLYBDENUM DINITROGEN

该项目的具体目标是(1)发现哪些类型的 二钨和二钼-酰肼(4-)络合物可在 金属处于其可能的最高氧化状态；(2)替换 这类化合物中的氯或烷基配体与硫酸盐配体在一个 努力尽可能接近与硫磺配位圈有关的 对固氮酶中钼周围的影响；(3)找出影响钼的因素 确定联氨或氨是由以下物质组合形成的 质子化/还原步骤；(4)设计和研究将 在两种相同或两种不同的金属之间配位氮气以 给出与先前制备的类似的Mu-肼(4-)络合物。 我们最近已经证明，有可能使钼氮络合物 通过还原钨(V)的单戊甲基环戊二烯络合物 氮素。这个环戊二烯体系似乎是最有可能的领域 寻找其他含有更多相关烷氧基或 结合在金属上的硫酸盐配体。它还应该可以扩展到 钼。 MX4型钼和钨的配合物(X=醇盐或 硫酸盐)是另一个勘探成熟的地区。 第三个领域涉及将两种金属同时连接在一起的配体的使用。 氮气合适的配位距离(约4.8A) 在这两种金属之间。配体，例如连接的环戊二烯配体， 二甲基间苯二酚或二甲基二硫代间苯二酚位居榜单前列。 最近发现的特别高的反应性 苯氧基取代烷基钨配合物向羰基转移 小组建议我们将能够制备乙烯基三烷氧基钨 亚烷基络合物和氮杂环丙烷的氮素络合物。 合成研究将得到电化学、x射线的补充。 最相关络合物的结构和拉曼光谱研究。

The specific aims of this project are (1) to discover what types of ditungsten and dimolybdenum Mu-hydrazido(4-) complexes can be prepared in which the metal is in its highest possible oxidation state; (2) to replace chloride or alkyl ligands in such complexes with thiolate ligands in an effort to come as close as possible to a sulfur coordination sphere related to that around molybdenum in nitrogenase; (3) to discover what factors determine whether hydrazine or ammonia is formed by a combination of protonation/reduction steps; (4) to design and study systems that will coordinate dinitrogen between two of the same or two different metals to give Mu-hydrazido(4-) complexes analogous to those previously prepared. We have recently shown that it is possible to make Mu-dinitrogen complexes by reducing a monopentamethylcyclopentadienyl complex of tungsten(V) under dinitrogen. This cyclopentadienyl system seems to be the most likely area to look for other dinitrogen complexes containing more relevant alkoxide or thiolate ligands bound to the metal. It also should be extendable to molybdenum. Both molybdenum and tungsten complexes of the type MX4 (X = alkoxide or thiolate) is another area ripe for exploration. A third area concerns the use of ligands that link two metals together at a distance that is appropriate (about 4.8A) for nitrogen to coordinate between the two metals. Ligands such as linked cyclopentadienyl ligands, dimethyl resorcinol, or dimethyl dithiaresorcinol are high on the list. The recent discovery of the especially high reactivity of phenoxide-substituted tungsten alkylidyne complexes toward the carbonyl group suggests that we will be able to prepare vinyltrialkoxytungsten dinitrogen complexes from alkylidyne complexes and azines. The synthetic studies will be complemented by electrochemical, x-ray structural, and Raman studies of the most relevant complexes.