Synthesis, structural investigations and corrosion inhibition studies on Mn(ii), Co(ii), Ni(ii), Cu(ii) and Zn(ii) complexes with 2-amino-benzoic acid (phenyl-pyridin-2-yl-methylene)-hydrazide
By Singh, Pooja; Singh, Divya Pratap; Tiwari, Karishma; Mishra, Monika; Singh, Ashish K. & Singh, Vinod P.
Published in RSC Adv.
The Royal Society of Chemistry
2015
Abstract
Mn(ii), Co(ii), Ni(ii), Cu(ii) and Zn(ii) complexes with 2-amino-benzoic acid (phenyl-pyridin-2-yl-methylene)-hydrazide (Habph) have been synthesized. The complexes were characterized by different physico-chemical and spectral studies viz. molar conductance, magnetic susceptibility measurements, electronic, IR and NMR spectra. The molecular structures of the ligand Habph and its Mn(ii), Ni(ii), Cu(ii), Zn(ii) complexes were further confirmed by single crystal X-ray diffraction technique. The Habph acts as a monobasic tridentate ligand coordinating through pyridyl-N, azomethine-N and enolate-O atoms with metal ions. Magnetic moments and electronic spectral studies suggest a high spin octahedral geometry for all the complexes. The ligand molecule exhibits a Z molecular conformation about the >C[double bond, length as m-dash]N- bond, whereas the metal complexes show E-configuration in their single crystal structures. The presence of inter- and intra-molecular H-bonding and various C-H[three dots, centered][small pi] interactions stabilize the molecular structure of the metal complexes. The structure of the Co(ii) complex has been satisfactorily modeled by density functional theory (DFT) and time dependent-DFT (TD-DFT) calculations. The results of electrochemical impedance spectroscopy (EIS) and adsorption behavior of the ligand and metal complexes show appreciable corrosion inhibition efficiency for mild steel in a 1 M HCl medi