Trinuclear Rhodium Complexes and Their Relevance for Asymmetric Hydrogenation |
| |
| Authors: | Angelika Preetz Wolfgang Baumann Hans‐Joachim Drexler Christian Fischer Jiangtao Sun Anke Spannenberg Oswald Zimmer Wolfgang Hell Detlef Heller |
| |
| Institution: | 1. Leibniz‐Institut für Katalyse e.?V. Albert‐Einstein‐Str. 29a, 18059 Rostock (Germany), Fax: (+49)?381‐128‐151‐183;2. Grünenthal GmbH, Zieglerstrasse 6, 52078 Aachen (Germany) |
| |
| Abstract: | Various trinuclear rhodium complexes of the type Rh3(PP)3(μ3‐OH)x(μ3‐OMe)2?x]BF4 (where PP=Me‐DuPhos, dipamp, dppp, dppe; different ligands and μ‐bridging anions) are presented, which are formed upon addition of bases such as NEt3 to solvate complexes Rh(PP)(solvent)2]BF4. They were extensively characterized by X‐ray diffraction and NMR spectroscopy (103Rh, 31P, 13C, 1H). Their in situ formation resulting from basic additives (NEt3) or basic prochiral olefins (without addition of another base) can cause deactivation of the asymmetric hydrogenation. This effect can be reversed by means of acidic additives. |
| |
| Keywords: | asymmetric catalysis hydrogenation rhodium kinetics phosphine ligands |
|
|
