Comparative Nucleophilic Displacement Reactions at Phosphorus and Silicon

磷和硅的亲核置换反应比较

• 批准号: 9526145
• 负责人: Robert Holmes
• 金额: $ 25.4万
• 依托单位: University of Massachusetts Amherst
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-02-15 至 1999-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9526145&HistoricalAwards=false
• 关键词: Comparative; Nucleophilic; Displacement; Reactions; Phosphorus

This award in the Inorganic, Bioinorganic, and Organometallic Chemistry Program provides continued support to Dr. Robert R. Holmes of the Chemistry Dearptment, University of Massachusetts at Amherst, for research on the reactivity of phosphorus and silicon compounds. During substitution reactions, phosphorus and silicon accommodate five or six groups around the central atom. Highly reactive species of this type will be synthesized, characterized using NMR spectroscopy, and modeled using ab initio methods and the capabilities of the San Diego supercomputer Center. Cyclic pentaoxyphosphoranes and isoelectronic five-coordinate anionic silicates will be the focus of the investigation. Substituents with rings of varying sizes and a variety of donor atoms will be prepared. The phosphorus work is expected to give information on the mechanism of hydrolysis of cyclic adenosine monophosphate, cAMP, while the silicon work models the initial stages of silanol polymerization. In both cases, the goal is to explore the formation of six-coordinate intermediates as the source of the increased reactivity observed for five-coordinate phosphorus and silicon compounds. The reaction rates for hydrolysis and solvolysis of the higher coordinate derivatives will be determined and compared to those of the lower coordinate species. Nitrogen donor atoms will be used in order to mimic the functions of amino acid residues present at the enzymatic active site and assess their role in forming higher coordinate intermediates. This research will determine the role of an alternate reaction pathway in two important cases. The possibility of six-coordinate intermediates affecting both reactivity and geometry in the physiologically important reaction of phosphoryl transfer or in the commercially important polymerization of silanol has not been previously explored.

该奖项在阿默斯特（Amherst）马萨诸塞大学的无机生物量学和有机金属化学计划中为持续支持，为磷和硅化合物的反应性研究提供了持续的支持。 在取代反应期间，磷和硅在中央原子周围可容纳五到六组。 这种类型的高反应性物种将被合成，使用NMR光谱法进行表征，并使用AB Initi算方法和圣地亚哥超级计算机中心的功能进行建模。 环状五氧氢磷酸和等异子五坐标阴离子硅酸盐将成为研究的重点。 将准备具有不同大小和各种供体原子的取代基。 预计磷的工作将提供有关环状腺苷单磷酸盐水解机理的信息，而硅的工作则建模了硅烷酚聚合的初始阶段。 在这两种情况下，目标都是探索六坐标中间体的形成，这是观察到的五层磷和硅化合物的反应性增加的来源。 将确定较高坐标衍生物的水解和溶解度的反应速率，并将其与较低坐标物种的反应速率进行比较。 将使用氮供体原子来模仿酶促活性位点存在的氨基酸残基的功能，并评估其在形成较高坐标中间体中的作用。 这项研究将确定在两个重要情况下替代反应途径的作用。 先前尚未探讨六坐标中间体在生理上重要的反应中影响反应性和几何反应的可能性。