Synthesis and characterization of copper(II), cobalt(II), nickel(II), and iron(III) complexes with two diamine Schiff bases and catalytic reactivity of a chiral diamine cobalt(II) complex

New transition metal complexes of Co(II), Cu(II), Ni(II), and Fe(III) of the ligands 6,6′-(1E,1′E)-(4,5-dimethyl-1,2-phenylene)bis(azan-1-yl-1-ylidene)bis(methan-1-yl-1-ylidene)bis(7-hydroxy-5-methoxy-2-methyl-4H-chromen-4-one) H₂L¹ and 6,6’-(1E,1′E)-cyclohexane-1,2-diylbis(azan-1-yl-1-ylidene)bis(methan-1-yl-1-ylidene)bis(7-hydroxy-5-methoxy-2-methyl-4H-chromen-4-one) H₂L² have been prepared and characterized using physio-chemical and spectroscopic methods. The results obtained for the complexes indicated that the geometries of the metal centres are either square planar or octahedral. Cyclopropanation reactions of unactivated olefins by ethyldiazoacetate (EDA) in the presence of [L¹Cu]·H₂O, [L²Cu]·2H₂O and [L²*Co]·2H₂O as catalysts were examined. The results showed that only [L²*Co]·2H₂O can act as a catalyst for the cyclopropanation reaction of unactivated olefins with very high selectivity (up to 99% based on EDA).