Functionalized cyclopentadienyl rhodium(iii) bipyridine complexes: synthesis, characterization, and catalytic application in hydrogenation of ketones
作者:Wan-Hui Wang、Yuki Suna、Yuichiro Himeda、James T. Muckerman、Etsuko Fujita
DOI:10.1039/c3dt50445j
日期:——
A series of highly functionalized cyclopentadienyl rhodium(III) complexes, [Cp′Rh(bpy)Br](ClO4) (Cp′ = substituted cyclopentadienyl), was synthesized from various multi-substituted cyclopentadienes (Cp′H). [Rh(cod)Cl]2 and Cp′H were firstly converted to [Cp′Rh(cod)] complexes, which were then treated with Br2 to give the rhodium(III) dibromides [Cp′RhBr2]2. The novel complexes [Cp′Rh(bpy)Br](ClO4) were obtained readily by the reaction of 2,2′-bipyridine with [Cp′RhBr2]2. These rhodium complexes [Cp′Rh(bpy)Br](ClO4) were fully characterized and utilized in the hydrogenation of cyclohexanone and acetophenone with generally high yields, but they did not exhibit the same reactivity trends for the two substrate ketones. The different activity of these complexes for the different substrates may be due to the influence of the substituents on the Cp′ rings.
以多种多取代环戊二烯(Cp′H)为原料,合成了一系列高功能化环戊二烯铑(III)络合物[Cp′Rh(mby)Br](ClO4)(Cp′=取代环戊二烯基)。首先将[Rh(cod)Cl]2 和 Cp′H 转化为[Cp′Rh(cod)]配合物,然后用 Br2 处理,得到铑(III)二溴化物[Cp′RhBr2]2。2,2′-联吡啶与[Cp′RhBr2]2反应,很容易得到新型络合物[Cp′Rh(bpy)Br](ClO4)。这些铑络合物[Cp′Rh(bpy)Br](ClO4)得到了充分表征,并被用于环己酮和苯乙酮的氢化反应,产量普遍较高,但它们对两种底物酮的反应趋势并不相同。这些配合物对不同底物的不同活性可能是由于 Cp′环上取代基的影响。