The mechanism of asymmetric homogeneous hydrogenation. Solvent complexes and dihydrides from rhodium diphosphine precursors
作者:John M. Brown、Penny A. Chaloner、Alexander G. Kent、Barry A. Murrer、Philip N. Nicholson、David Parker、Philip J. Sidebottom
DOI:10.1016/s0022-328x(00)85766-6
日期:1981.8
no affinity for hydrogen. R-Phenyl bis-diphenylphosphinoethane falls into this category, but the 31P NMR spectra of its complexes demonstrate an equilibrium between monomeric and dimeric species, and addition of triethylamine gives rise to a trimer. trans-Chelating biphosphines show more variable behaviour, and in the case of bis-1,5-diphenylphosphinopentane, a number of complexes, including one requiring
双环[2,2,1]庚-2,5-二烯和环辛-1,5-二烯(联膦)铑四氟硼酸酯在1个大气压下在甲醇或其他极性溶剂中与氢反应。初始产物可以是溶剂化的二氢化物或溶剂化物。根据磷化氢的结构,这两种物质之间的平衡差异很大。当配体为单膦时,二酐通常是稳定的产物,尽管(邻-甲氧基苯基)甲基苯基膦是一个例外。顺式螯合双膦通常形成对氢没有亲和力的溶剂合物。R-苯基双-二苯基膦基乙烷属于此类,但31其配合物的1 H NMR光谱表明单体和二聚体之间达到平衡,三乙胺的添加产生三聚体。反式螯合双膦具有更多的可变性,并且在双1,5-二苯基膦基戊烷的情况下,观察到许多复合物,包括需要CHH活化的复合物。