A novel ligand HL (1). N,2-bis(1-(2-oxo-2H-chromen-3-yl)ethylidene)hydrazinecarbothioamide was synthesized through the condensation of 3-acetyl-2H-chromen-2-one and hydrazinecarbothioamide. This ligand was used to prepare new transition metal complexes Of Cu(II), Ni(II) and Co(II). Characterization of the HL (1) ligand and its complexes is also reported. Mass spectra and NMR assignments to[the ligand, 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 octahedral, or Square planar. The structures are consistent with the IR, UV-vis, ESR, as well as conductivity measurements. The catalytic activity of the copper complex, [HLCu2Cl3]Cl center dot H2O (2), in cyclopropanation reactions of unactivated olefins with ethyldiazoacetate (FDA) was studied. Cyclopropanes were obtained in high yield (up to 97%. TON Up to 16,900) with moderate to good diastereoselectivities (50-91%). (C) 2009 Elsevier B.V. All rights reserved.