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• Novel Mn(P,N) and Mn(P,N,N) complexes were synthesized and characterized. • The complexes were applied in asymmetric hydrogenation of ketones. • The P-N and N-N tether length strongly affect coordination and catalytic properties. • High activities and enantioselectivities (up to 95%) were obtained. • A qualitative stereochemical model explaining enantioselectivity has been proposed. Manganese complexes modified by simple alkane-diyl based P,N (Ph 2 PCH(CH 3)(CH 2) m CH(CH 3)NHC 2 H 5 ; m = 0, 1) and potentially tridentate P,N,N (Ph 2 PCH(CH 3)(CH 2) m CH(CH 3)NH(CH 2) n N(CH 3) 2 ; m = 0, 1; n = 2, 3) type ligands have been synthesized and tested in the asymmetric hydrogenation of ketones. The combined coordination and catalytic studies led to the conclusion that the N-N tether length of the P,N,N type compounds plays a crucial role in determining the chemoselectivity, while the length of the P-N skeleton has been shown to affect the catalytic activity. Mn-catalysts containing P,N,N ligands with the proper tether lengths (m = 0, n = 1) provided high enantioselectivities (up to 95% ee) and activities in the asymmetric hydrogenation of acetophenone derivatives. The influence of substitution of the acetophenone substrate and the reaction conditions is demonstrated. Based on quantum chemistry calculations, a qualitative model explaining the origin of enantioselectivity is proposed. [Display omitted] [ABSTRACT FROM AUTHOR]

• Novel Mn(P,N) and Mn(P,N,N) complexes were synthesized and characterized. • The complexes were applied in asymmetric hydrogenation of ketones. • The P-N and N-N tether length strongly affect coordination and catalytic properties. • High activities and enantioselectivities (up to 95%) were obtained. • A qualitative stereochemical model explaining enantioselectivity has been proposed. Manganese complexes modified by simple alkane-diyl based P,N (Ph 2 PCH(CH 3)(CH 2) m CH(CH 3)NHC 2 H 5 ; m = 0, 1) and potentially tridentate P,N,N (Ph 2 PCH(CH 3)(CH 2) m CH(CH 3)NH(CH 2) n N(CH 3) 2 ; m = 0, 1; n = 2, 3) type ligands have been synthesized and tested in the asymmetric hydrogenation of ketones. The combined coordination and catalytic studies led to the conclusion that the N-N tether length of the P,N,N type compounds plays a crucial role in determining the chemoselectivity, while the length of the P-N skeleton has been shown to affect the catalytic activity. Mn-catalysts containing P,N,N ligands with the proper tether lengths (m = 0, n = 1) provided high enantioselectivities (up to 95% ee) and activities in the asymmetric hydrogenation of acetophenone derivatives. The influence of substitution of the acetophenone substrate and the reaction conditions is demonstrated. Based on quantum chemistry calculations, a qualitative model explaining the origin of enantioselectivity is proposed. [Display omitted] [ABSTRACT FROM AUTHOR]