The Chemistry of Organosamarium(II) and Related Complexes

无机化学、生物无机化学和金属有机化学计划中的这个项目涉及到稀土金属的有机金属化学，特别是钐。首席研究人员已经证明，有机钼配合物是一种非常强大的还原剂，具有可溶于多种常见有机溶剂的优点，在这些溶剂中，它们可以实现有机分子的各种非常不寻常的转化。对这些络合物的进一步研究有望更好地确定它们作为合成试剂的用途，并提供对它们的化学反应的了解。本项目的目的是确定控制有机稀土(II)络合物，特别是有机铵(II)络合物的特殊反应性的因素。特别令人感兴趣的是一系列相关的Sm(II)介导的反应，在这些反应中，碳-碳双键或三键或氮-氮双键被激活，并与CO反应，得到显著的转化产物。这将为探索Sm(II)的反应性原理提供极好的机会，因此将进行详细的研究。这一化学将扩展到C-C键断裂反应和使用Sm(II)生成的二羟甲酰基配合物来实现直链烷基的环化。通过研究在双(五甲基环戊二烯)-双(THF)Sm(III)和双(五甲基环戊二烯)-(THF)Eu(II)存在下的外部还原转化，考察Lewis酸中心对Sm(II)反应的影响。这些实验的结果，加上对影响还原Sm-O键断裂的方法的研究，有望导致在Sm中催化的还原转化体系。还将探讨反应性桥联双金属Sm(II)试剂的合成，以及双(五甲基环戊二烯)Sm(II)不寻常的弯曲结构在该试剂活化烯烃中的化学后果。

This project in the Inorganic, Bioinorganic and Organometallic Chemistry Program deals with the organometallic chemistry of the lanthanide metals, especially samarium. Organosamarium complexes have been shown by the Principal Investigator to be unusually powerful reducing agents which have the advantage of being soluble in a number of common organic solvents, in which they effect a variety of highly unusual transformations of organic molecules. Further studies of these complexes are expected both to define better their utility as synthetic reagents and to provide an understanding of their chemical reactivity. The objective of this project is to determine the factors which control the special reactivity of organolanthanide(II) complexes, especially of organosamarium(II) complexes. Of special interest is a series of related Sm(II)-mediated reactions in which carbon-carbon double or triple bonds, or nitrogen-nitrogen double bonds, are activated and reacted with CO to give significantly transformed products. These will provide excellent opportunities to probe the principles of Sm(II) reactivity and therefore will be studied in detail. This chemistry will be extended to C-C bond cleavage reactions and the use of Sm(II)-generated dihaptoacyl complexes to effect cyclization of straight-chain alkyls. The effect of the Lewis acid center on Sm(II) reactions will be examined by studying reductive transformations using an external reductant in the presence of bis(pentamethylcyclopentadiene)- bis(THF)samarium(III) and bis(pentamethylcyclopentadiene)- (THF)europium(II). The results of these experiments, together with studies of methods for effecting reductive Sm-O bond cleavage, are expected to lead to reductive transformation systems which are catalytic in samarium. The synthesis of reactive bridged bimetallic Sm(II) reagents will be explored also, as will the chemical consequences of the unusual bent structure of the bis(pentamethylcyclopentadiene)samarium(II) in the activation of alkenes by this reagent.