Comparative Nucleophilic Displacement Reactions at Phosphorus and Silicon

该奖项在无机，生物无机和有机化学 该计划为罗伯特·R博士提供持续支持。霍姆斯 马萨诸塞州大学化学系， Amherst，用于高价硅的研究， 磷化合物 阴离子六配位硅 将制备化合物，并将其特性 与类似的磷化合物相比。 无环，五氧基， 阴离子硅酸盐将进行研究，以了解更多 关于硅烷醇聚合的初始步骤。 的 五配位化合物结构和构象性质 磷和硅化合物，含有不同的环， 将研究从6元到8元的尺寸，特别是当 与cAMP机制有关。 同样需要调查的是 亲核取代反应的机理途径 四配位的磷和硅。 广泛的工具 将用于表征化合物，包括变量 温度NMR、X射线衍射和分子建模。 %%% 直到最近才有可能比较 具有五个或六个连接到硅上的基团的硅化合物 类似磷化合物的行为。 通过 通过比较这些化合物 重新排列或丢失第五或第六组， 了解空间和电子因素如何影响 这些化合物的化学性质。 这项基础研究 该项目可能有助于深入了解硅的形成 聚合物或核苷环的水解 3'，5'-单磷酸盐，其在细胞中起核心作用。 调节细胞代谢。

This award in the Inorganic, Bioinorganic, and Organometallic Program provides continued support to Dr. Robert R. Holmes of the Chemistry Department, University of Massachusetts at Amherst, for the investigation of high valent silicon and phosphorus compounds. Anionic, hexacoordinated silicon compounds will be prepared and their characteristics will be compared to analogous phosphorus compounds. Acyclic, pentaoxy, anionic silicates will be studied in order to understand more concerning the initial steps in silanol polymerization. The structure and conformational properties of pentacoordinte phosphorus and silicon compunds containing rings varying in size from 6- to 8- membered will be studied, particularly as relevant to cAMP mechanisms. Also to be investigated is the mechanistic pathway for nucleophilic displacement reactions of tetracoordinate phosphorus and silicon. A wide range of tools will be used to characterize the compounds, including variable temperature NMR, X-ray diffraction, and molecular modeling. %%% Only recently has it become possible to compare the behavior of silicon compounds with five or six groups attached to silicon to the behavior of analogous phosphorus compounds. By comparing the details of reactions in which such compounds rearrange or lose the fifth or sixth group, it is possible to understand more about how spatial and electronic factors affect the chemistry of these compounds. This fundamental research project may help provide insight into the formation of silicon polymers or into the hydrolysis of nucleoside cyclic 3',5'-monophosphates, which play a central role in the regulation of cell metabolism.