MnII complexes with tetradentate N4 ligands: Highly efficient catalysts for the epoxidation of olefins with H2O2

A series of Mn-complexes with tetradentate N4 ligands, introducing aromatic groups into 2-pyridylmethyl positions of N,N′-dimethyl-N,N′-bis(2-pyridylmethyl)ethane-1,2-diamine (mep), N,N′-dimethyl-N,N′-bis(2-pyridylmethyl)cyclohexane-trans-diamine (mcp), have been synthesized and applied for epoxidation of olefins using H2O2 as the oxidant. The Mn-complexes still possessed an octahedral mononuclear structure in a cis-α topology. These complexes showed good regioselectivity, high yields and turnover frequency (even up to 228,000 h−1) with low catalyst loading (0.1–0.01 mol%) for epoxidation of a family of olefins (including internal aromatic olefins, internal and terminal aliphatic olefins and diolefins).

Graphical abstractA series of Mn-complexes with tetradentate N4 ligands have been synthesized and applied for the epoxidation of olefins using H2O2 as the oxidant. The complexes 1 and 3 (C1 and C3) showed excellent selectivity, high yields and turnover frequency (even up to 228,000 h−1) with low catalyst loading (0.1–0.01 mol%) for epoxidation of a family of olefins (including internal aromatic olefins, internal and terminal aliphatic olefins and diolefins).Figure optionsDownload full-size imageDownload high-quality image (98 K)Download as PowerPoint slideHighlights► A series of tetradentate N4 Mn-complexes have been synthesized and characterized. ► The topologies of these Mn-complexes have been determined by the X-ray diffraction. ► C1 and C3 showed excellent selectivity, high yields and TOF with low catalyst loading for the epoxidation of a family of olefins with H2O2.