Rh(I) coordination chemistry of hexacationic Dendriphos ligands and their application in hydroformylation catalysis

详细信息    查看全文

• 作者：Dennis J.M. Snelders ; Katharina Kunna ; Christian Mü ; ller ; Dieter Vogt ; Gerard van Koten ; Robertus J.M. Klein Gebbink
• 刊名：Tetrahedron: Asymmetry
• 出版年：2010
• 出版时间：23 June 2010
• 年：2010
• 卷：21
• 期：11-12
• 页码：1411-1420
• 全文大小：550 K

文摘

The coordination chemistry of hexacationic Dendriphos ligands L* with respect to Rh(I), as well as their application in Rh-catalyzed hydroformylation reactions, is described. Complexes of the type RhCl(CO)(L*)₂ were synthesized and characterized. The results show that Dendriphos ligands are weaker σ-donors and/or stronger π-acceptors compared to PPh₃. The reaction of L* with [Rh(cod)₂]BF₄ in MeCN afforded monophosphine-Rh(I) complexes of the type Rh(cod)(MeCN)(L*), which points to the tendency of these ligands to form coordinatively unsaturated metal complexes. The catalytic performance of Dendriphos ligands in the Rh-catalyzed hydroformylation appeared to be dominated by steric effects arising from the large dendritic shells of these ligands. Furthermore, the possibility of tuning the catalytic activity and selectivity of the catalytic species, by changing the six counteranions of the hexacationic Dendriphos ligand, has been investigated. Changing the anions from to the chiral anions camphorsulphonate or Δ-Trisphat did not render the hydroformylation reaction of styrene enantioselective, albeit small changes in its regioselectivity were observed.