Bis(methoxyethyldimethylphosphine)ruthenium(II) Complexes as Transfer Hydrogenation Catalysts

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Journal Title, Volume, Page: 
Zeitschrift für anorganische und allgemeine Chemie Volume 629, Issue 7-8, pages 1308–1315, July 2003
Year of Publication: 
2003
Authors: 
Zhong-Lin Lu
Tübingen, Institut für Anorganische Chemie der Universität
Klaus Eichele
Tübingen, Institut für Anorganische Chemie der Universität
Ismail Warad
Tübingen, Institut für Anorganische Chemie der Universität
Current Affiliation: 
Department of Chemistry, Faculty of Science, An-Najah National University, Nablus, Palestine
Hermann A. Mayer
Tübingen, Institut für Anorganische Chemie der Universität
Ekkehard Lindner
Tübingen, Institut für Anorganische Chemie der Universität
Zheng-jing Jiang
Tübingen, Institut für Organische Chemie der Universität
Volker Schurig
Tübingen, Institut für Organische Chemie der Universität
Preferred Abstract (Original): 
Diamineruthenium(II) complexes containing the hemilabile methoxyethyldimethylphosphine ligand, [Cl2Ru(Ln)(η1-Me2PCH2CH2OMe)2] (2Ln) (n = 1-12, Scheme 1), have been synthesized from the starting materials Me2PCH2CH2OMe, [Ru(COD)Cl2]n, and the respective diamines L1-L12. The structure of complex 2L5 reveals that two chlorides are in trans position, while in complex 2L11 the two chlorides favor a cis configuration. Most of the complexes are highly catalytic active in the hydrogen transfer reduction of acetophenone. The experimental study indicates that the replacement of phenyl groups for methyl functions in the ether-phosphine ruthenium(II) complexes resulted in a switch of the hydrogenation mechanism from direct hydrogenation to transfer hydrogenation. The reason is attributed to the better donor ability of methyl groups compared to phenyl substitutents. Thus the metal center becomes more electron-rich and inhibits the binding of dihydrogen to the ruthenium(II) complex fragment.
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