Synthesis and characterization of new schiff base metal complexes and their use as catalysts for olefin cyclopropanation

摘要

New transition metal complexes of CoII, CuII, NiII, and FeIII of the ligands 2N,2-bis((7- hydroxy-5-methoxy-2-methyl-4-oxo-4H-chromen-6-yl)methylene) hydrazinecarbo-thioamide H3L1 and (E)-2-((7-hydroxy-5-methoxy-2-methyl-4-oxo-4H- chromen-6-yl)methylene)-N- phenylhydrazinecarbothioamide H2L2 have been prepared and characterized. Mass spectra and NMR assignments for the ligands, using COSY, NOESY homonuclear, and HMQC and HMBC heteronuclear correlation techniques were carried out. Electronic and magnetic moments of the complexes indicate that the geometries of the metal centers are either distorted square pyramidal or octahedral. The structures are consistent with the IR and UV-VIS, as well as conductivity and magnetic moments measurements. Cyclopropanation reactions of unactivated olefins by ethyldiazoacetate (EDA) in the presence of H3L1Cu2.Cl4.H2O as catalyst proceed with excellent turn over numbers (TON: up to 12556). Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.