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

在无机、生物无机和有机金属化学项目的这个项目中，Richard Eisenberg博士将利用他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制。这种现象导致核磁共振信号大大增强，并有望在金属-氢相互作用研究中最重要的工具之一得到重大改进。该项目的重点是铂族配合物的化学性质。在所研究的配合物中，大多数配体是桥接和非桥接的二（叔膦）基，也有一些氢化物配体。该项目的一个主要推力是对氢诱导极化（PHIP），当使用对富二氢进行氢化和加氢反应时，会产生不寻常的核磁共振增强。对PHIP的观察提供了涉及双氢成对转移的反应机制的明确证据。将要进行的具体研究将：a)分析PHIP的动力学意义；b)用PHIP观察催化意义显著的氢化物和中间体；c)用富集对氢的二氢检测不对称加氢和团簇氢解反应；d)利用PHIP增强P-31和C-13核磁共振波谱中的核磁共振信号。第二个重点是金属配合物促进硅烷的反应，主要目的是催化硅-硅键的形成。一系列的研究将探讨原硅烷与双核配合物的反应，最初导致与双（硅）桥的配合物。SiRH单元的后续耦合将通过金属中心的配位控制、氧化还原促进反应和光分解来探索。硅烷脱氢偶联产生的二氢将通过适当的烯烃加氢来脱除。在一系列相关的研究中，单核双核和三核（硅基）配合物将被检查关于Si-H和Si-Si还原消除。硅基配合物的其他反应，如硅氢化反应也将进行研究。

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.