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A new type of trans‐dichloro‐Ir(III) complexes derived from non‐symmetrical NacNac‐type ligands was unexpectedly obtained as the main reaction product from the former ligands and the dimeric species [Ir(COD)Cl2]. One equivalent of LH was reacted with an excess of [Ir(COD)Cl]2 in dichloromethane or toluene as solvent and at room temperature. The general formula of the product is [IrCl2(COD)L] and was isolated as a sole product instead of the expected Ir(I) compound [Ir(COD)L]; all the new Ir(III) were prepared in high yields as microcrystalline solids. They were all stable under laboratory atmosphere, lasting for weeks in solution and for months in solid state. The structure of each compound was examined by 1D and 2D nuclear magnetic resonance (NMR) and high‐resolution mass spectrometry (HRMS). Complex 1k was selected for an X‐ray diffraction study. Finally, an evaluation was made of the catalytic activity of all complexes in the transfer hydrogenation reaction of ketones and imines. [ABSTRACT FROM AUTHOR]

A new small family of Ru, Rh, and Ir piano-stool complexes partially containing the bulky acac diMes , p -Cymene and Cp* ligands was synthetized and characterized. Their catalytic activity in transfer hydrogenation reaction was tested. The turn over frequency (TOF) values for aromatic- and alkyl-ketones giving the corresponding desired alcohols were increased in two orders of magnitude by using microwave heating compared with conventional thermal method. Ru, Rh and Ir β-Dimesitylaceonate piano stool complexes were used as catalytic precursors on the transfer hydrogenation reaction; the microwave irradiation heating raise the TOF values in two order of magnitude comparing with the thermal conditions. Image 1 [ABSTRACT FROM AUTHOR]