Chemical Reactivity of Electronically Excited Transition Metal Complexes

金属簇合物是一类重要的催化剂， 作为物种的模型， 当它们被用作 催化剂的这种簇合物强烈吸收光， 由此形成的高能（激发态）物质 非常活跃， 有机分子该研究项目预计将提供 有效使用金属所必需的信息 团簇作为光诱导化学反应的催化剂。 该研究的重点是提供一般的 多电子光化学指南 过渡金属化合物的种类：多键金属- 金属（M-n-M）二聚体和Mo（II）的六核簇合物， W（II）.这些化合物的激发态是高度 发光且寿命长。控制兴奋的因素 六核团簇和M-n-M二聚体的态动力学 将使用电子吸收、发射和 时间分辨光谱初步数据表明 这些物质的氧化还原化学是由 从金属芯中分离出来这些研究将通过使用 循环伏安法、计时电流法和电生 化学发光（ECL）以鉴定反应途径。的 特别重要是ECL将用于 探讨六核团簇的几个机理特征 氧化还原过程。光谱系统和 电化学研究是互补的，将用于 定义一个框架，在其中构建多电子 激发态金属簇的转变。激发态 反应途径依赖于氧化还原反应的小 分子反应物和有机底物在电子 激发的，配位不饱和的金属簇核将被 开发

Metal cluster compounds are an important class of catalysts and are also of substantial current interest as models of species which exist at the metal surfaces when they are used as catalysts. Such cluster compounds absorb light strongly and the high-energy (excited state) species which are formed thereby are very reactive in bringing about chemical transformations of organic molecules. This research project is expected to provide information which is essential to effective use of metal clusters as catalysts for light-induced chemical reactions. The proposed research is focused on providing general guidelines for multielectron photochemistry beginning with two classes of transition metal compounds: multiply bonded metal- metal (M-n-M) dimers and hexanuclear clusters of Mo(II) and W(II). The excited states of these compounds are highly luminescent and long-lived. The factors governing the excited state dynamics of the hexanuclear clusters and the M-n-M dimers will be defined using electronic absorption, emission and time-resolved spectroscopies. Preliminary data indicate that the oxidation-reduction chemistry of these species is derived from the metal cores. The studies will be extended by using cyclic voltammetry, chronoamperometry and electrogenerated chemiluminescence (ecl) to identify reaction pathways. Of special importance are experiments in which ecl will be used to probe several mechanistic features of the hexanuclear cluster oxidation-reduction processes. The spectroscopic and electrochemical studies are complementary and will be used to define a framework in which to construct multielectron transformations of excited state metal clusters. Excited state reaction pathways that rely on redox reactions of small molecule reactants and organic substrates at electronically excited, coordinatively unsaturated metal cluster cores will be developed.