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Since 1990s asymmetric transfer hydrogenation (ATH) of ketones has become a versatile and powerful method for production of enantiomerically pure secondary alcohols, when highly enantioselective catalysts [(arene)RuCl(Ts-DPEN)]1 and [Cp*MCl(Ts-DPEN)]2 (M = Rh, Ir) (DPEN = 1,2-diamino-1,2-diphenylethane) were discovered. The demand to achieve higher activities resulted in finding extremely active [(Josiphos)RuCl{κ3-C,N,N-1-(6-arylpyridin-2-yl)methanamines}]3 and [(p-cymene)RuCl{1-(Pr2P)-2-(NMe2)-Indenyl}]4, which hydrogenate aromatic ketones in isopropanol with TOF up to 105 – 106 h-1. Despite more than 20 years of development, prognosing the activity of such catalysts is however still a hard task, and the search for novel promosing TH catalysts is of great interest. Recently we have reported on synthesis and chemical properties of a series of 18ē and 16ē half-sandwich arene ruthenium iminophosphonamide (NPN) complexes [(arene)Ru{(R2P(NR’)2}(X)] (X = Cl or PF6-, BAr4-),5 which are isoelectronic to and structural analogues of Noyori catalysts. We found that the zwitter-ionic NPN ligand is a strong σ,-donor and can efficiently stabilize coordinatively unsaturated 16ē NPN complexes. Here we present first examples of catalytic transfer hydrogenation of acetophenone (Acp) with NPN-complexes [(arene)Ru{(Ph2P(NTol)2}(X)] (arene: (a) p-cymene, (b) C6Me6) in isopropanol. Without base only 18ē NPN-complexes (X = Cl) slowly catalyze reduction of Acp (TOF ~ 10 h-1), however addition of 1 equiv. of strong base makes both 18ē and 16ē complexes active (TOF ~ 200 h-1). For a p-cymene complex we have thoroughly scrutinized the mechanism of the catalysis by studying its kinetics, performing a model studies as well as by DFT calculations. A tentative catalytic cycle is given on the scheme below, the numbered intermediates and off-loop species were either isolated or identified spectroscopically. The activity of the NPN-complexes with C6Me6 ligand were found to be significantly lower due to increased stability of the isopropoxide complex 2 towards β-hydrogen elemination that correlates well with higher enthalpy of dissociation (ΔHd) of Ru-Cl bond in 1b compared to 1a. Thus the rate-limiting step is supposed to be the β-hydrogen elemination of the alkoxide complex. The investigation of the effect of the N- and P- substituents is in progress.