Synthesis and characterization of some Schiff bases derived from orthophthalaldehyde and their bridged complexes with Co (II) and Ni (II) as corrosion inhibitors for carbon steel in acidic medium

Abstract

In this study, two Schiff base ligands, L1 and L2derived from ortho-phthalaldehyde and primary amines (4-aminopyridine and 4-aminobenzothiazole) were studied using infrared spectroscopy (IR), proton nuclear magnetic resonance spectroscopy ( 1HNMR), carbon- . 13 atomic magnetic coupled resonance spectroscopy (13 CNMR ), mass spectrometry, and also were performed by elemental analysis ,and then reacted with tetrathiocyanates in a 1:1 molar ratio with Schiff base ligands synthesized to produce diatomic mixed-metal-bridge complexes as (L MCd(SCN) 4), where M represents Co(II) or Ni(II) .These complexes were characterized by spectroscopic methods and magnetic susceptibility measurements .The results showed that all the complexes had the same coordination number of four. In addition, the cobalt complex exhibited paramagnetic properties, while the nickel complex exhibited diamagnetic properties. The synthesized Schiff base ligands were evaluated as an inhibitor of carbon steel corrosion in acidic medium and showed good inhibitory activity.