Comparative Nucleophilic Displacement Reactions at Phosphorus and Silicon

这个无机、生物无机和有机金属项目的奖项为马萨诸塞大学阿默斯特分校化学系的Robert R. Holmes博士对高价硅和磷化合物的研究提供了持续的支持。阴离子、六配位硅化合物将被制备，它们的特性将与类似的磷化合物进行比较。无环，五氧，阴离子硅酸盐将进行研究，以了解更多关于硅醇聚合的初始步骤。将研究含有6- 8元环的五配位磷和硅化合物的结构和构象性质，特别是与cAMP机制有关的结构和构象性质。四配位磷和硅的亲核置换反应的机理途径也有待研究。广泛的工具将用于表征化合物，包括变温核磁共振，x射线衍射和分子模型。直到最近才有可能把硅上有5或6个基团的硅化合物的行为与类似的磷化合物的行为进行比较。通过比较这些化合物重新排列或失去第五或第六基团的反应细节，有可能更多地了解空间和电子因素如何影响这些化合物的化学性质。这个基础研究项目可能有助于深入了解硅聚合物的形成或核苷环3',5'-单磷酸的水解，这在细胞代谢的调节中起着核心作用。

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.