Synthesis, IR-, NMR-, DFT- and X-ray analysis of novel C2-chiral diferrocenyl–salen complexes

Chiral salen complexes with C2-symmetry were prepared by the complexation of a selection of transition metal salts with a novel ligand obtained via controlled diastereoselective diaza-Cope rearrangement of a diimine which was resulted from the condensation 2,2′-[(1R,2R)-1,2-diaminoethane-1,2-diyl]diphenol with formylferrocene. On the effect of air the iron(II)-complex dissolved in DCM underwent oxidation affording a square pyramidal iron(III)-complex with coordinated chlorine atom in the apical position. It was also found that the two ferrocenyl groups present in the cobalt(II)-complex remained intact in the course of iodine-mediated oxidation leading a diamagnetic cobalt(III)-complex. The structures of the new compounds were established by single crystal x-ray diffraction as well as IR 1H-, 13C- and 15N NMR spectroscopy.

Graphical abstractChiral salen complexes with C2-symmetry were prepared by the complexation of a selection of transition metal salts with a novel ligand containing two ferrocenyl groups. The structures of the complexes were determined by spectroscopic methods, DFT modelling and single crystal x-ray diffraction.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Facile synthesis of a novel 1,2-diferrocenylethane-1,2-diamine-based C2-chiral salen ligand. ► Construction and structure of a series of its transition metal complexes. ► DFT modelling of the complexes susceptible to oxidation.