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μ-肼基（4-）配合物可以在 金属处于其最高可能的氧化态;（2）取代 氯化物或烷基配体与硫醇盐配体的络合物， 尽可能接近硫配位圈的努力 固氮酶中钼的作用;（3）找出影响固氮酶活性的因素 确定肼或氨是否由以下物质的组合形成： 质子化/还原步骤;（4）设计和研究系统， 在两种相同或两种不同的金属之间配位二氮， 得到与先前制备的那些类似的μ-肼基（4-）配合物。 我们最近表明，可以制备Mu-双氮复合物 通过还原钨（V）的五甲基硼络合物， 二氮 这个星系似乎是最有可能 寻找含有更多相关醇盐的其他二氮络合物， 与金属结合的硫醇盐配体。 它也应该是可扩展的， 钼。 MX4型钼和钨络合物（X =醇盐或烷氧基化物）均为金属。 硫醇盐）是另一个成熟的勘探领域。 第三个领域涉及使用配体将两种金属以一定的配位键合在一起。 适合氮配位的距离（约4.8A） 两种金属之间。 配体例如连接的环戊二烯基配体， 二甲基间苯二酚或二甲基二硫杂间苯二酚在名单上名列前茅。 最近发现的特别高的反应性， 苯氧取代的钨烷撑配合物对羰基 小组建议，我们将能够制备乙烯基三烷氧基钨 二氮络合物来自亚烷基络合物和吖嗪。 合成研究将辅以电化学，X射线， 结构和拉曼研究的最相关的复合物。

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.