Mononuclear diastereopure non-heme Fe(II) complexes of pentadentate ligands with pyrrolidinyl moieties: Structural studies, and alkene and sulfide oxidation

Mononuclear iron(II) complexes of enantiopure Py(ProOH)2 (2) and Py(ProPh2OH)2 (3) ligands have been prepared with FeCl2 and Fe(OTf)2 · 2MeCN. Both ligands coordinate to the metal in a pentadentate fashion. Next to the meridional N,N′,N-coordination of the ligand, additional coordination of the oxygen atoms of both hydroxyl groups to the metal is found in complexes 4–7. Complex [FeCl(2)](Cl) (4) shows an octahedral geometry as determined by X-ray diffraction and is formed as a single diastereoisomer. The solution structures of complexes 4–7 were characterized by means of UV–Vis, IR, ESI-MS, conductivity and CD measurements. The catalytic potential of these complexes in the oxidation of alkenes and sulfides in the presence of H2O2 is presented.

Graphical abstractThe chiral prolinol-derived ligands Py(ProOH)2 and Py(ProPh2OH)2 form diastereopure hexa-coordinated Fe(II) complexes with one labile coordination side. These complexes are able to oxidize alkenes to epoxides with modest product selectivities. In addition, sulfides are oxidized to sulfoxides with high product selectivities, but with low ee’s.Figure optionsDownload full-size imageDownload as PowerPoint slide