Chemistry and Applications to Catalysis of Phosphine Complexes of the Platinum Group Elements

在无机化学、生物无机化学和金属有机化学计划的这个项目中，理查德·艾森伯格博士将利用他的实验室最近发现的一种新现象-对氢诱导极化-来研究各种有机金属反应的机理。这一现象导致核磁共振信号大大增强，有望显著改进用于研究金属-氢相互作用的最重要工具之一。该项目的重点是铂族络合物的化学。对于所研究的配合物，大多数配体是桥联和非桥联的二(叔膦)基，也有一些氢化物配体。该项目的一个主要目的是对氢致极化(PhIP)，当使用富含对位的二氢进行氢化和氢加成反应时，会产生不寻常的核磁共振增强。PhIP的观察为反应机理提供了确凿的证据，该反应机理涉及两个氢气的转移。将进行的具体研究将：a)分析PhIP的动力学意义；b)使用PhIP观察具有催化意义的氢化物和中间体：c)研究不对称氢化反应和使用对位富集氢的簇氢分解反应；以及d)使用PhIP增强P-31和C-13核磁共振谱中的核磁共振信号。第二个重点是金属络合物促进的硅烷反应，其主要目标是催化硅-硅键的形成。一系列研究将研究伯硅烷与双核络合物的反应，最初会导致双(硅烯)桥的络合物。后续SiRH单元的耦合将通过金属中心的配位控制、氧化还原促进的反应和光解来探索。硅烷脱氢偶联产生的二氢的脱除将通过适当的烯烃加氢来完成。在一系列相关的研究中，将考察单核、双和三(硅基)配合物对硅-氢和硅-硅还原消除的影响。还将研究硅基络合物的其他反应，如硅氢化反应。

In this project in the Inorganic, Bioinorganic and Organometallic Chemistry Program Dr. Richard Eisenberg will take advantage of a new phenomenon recently discovered in his laboratory, para hydrogen induced polarization, in the study the mechanisms of a variety of organometallic reactions. This phenomenon leads to greatly enhanced nuclear magnetic resonance signals, with the promise of significant improvements in one ofthe most important tools used in the study of metal-hydrogen interactions. The focus of the project is the chemistry of platinum group complexes. For the complexes under study most of the ligands are bridging and non-bridging di(tertiary phosphine) groups, with some hydride ligands as well. A major thrust of the project is para hydrogen induced polarization (PHIP) in which unusual NMR enhancements result when hydrogenation and hydrogen addition reactions are performed using para enriched dihydrogen. Observation of PHIP provides definitive evidence of a reaction mechanism involving pairwise transfer of dihydrogen. The specific studies to be performed will: a) analyze PHIP for its kinetic significance; b) use PHIP to observe catalytically significant hydrides and intermediates: c) examine asymmetric hydrogenation and cluster hydrogenolysis reactions using para enriched dihydrogen; and d) use PHIP to enhance NMR signals in P-31 and C-13 NMR spectroscopy. A second thrust focuses on metal complex-promoted reactions of silanes with the principal objective of catalyzing Si-Si bond formation. One series of studies will investigate the reactions of primary silanes with binuclear complexes leading initially to complexes with bis(silylene) bridges. Subsequent coupling of SiRH units will be probed through coordination control of the metal centers, by redox-promoted reactions, and by photolyses. Removal of dihydrogen generated in dehydrogenative coupling of silanes will be done by hydrogenating an appropriate olefin. In a related series of studies mononuclear bis- and tris(silyl) complexes will be examined with regard to Si-H vs Si-Si reductive elimination. Other reactions of silyl complexes such as hydrosilation will be studied also.