An-Najah Staff

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.

The ligands exchange of the ether-phosphine (Ph2PCH2CH2OCH3) on the diamine(ether-phosphine)ruthenium(II) with 1,3-bis(diphenylphosphino)propane as a bidentate chelate ligand successfully occurs to produce diamine[1,3-bis(diphenylphosphino)propane]ruthenium(II) complexes in a good yields under vigorous stirring for one week in an inert atmosphere using dichloromethane as solvent. Several ether-phosphine-RuC12 complexes with different types of diamine have been tested to confirm the substitution method. In order to collect more information about the system 31P{1H} NMR and 13C{1H} NMR as well as FAB- Mass spectroscopy have been investigated in parallel way to control and support the ligands exchange reaction processes.