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)-hydrazideElectronic supplementary information (ESI) available: 1H & 13C NMR spectra of Habph and Zn(ii) complex, and π π & C-H π interactions in different compounds; Tables for theoretical structural parameters. CCDC 894885, 988159, 988158, 988160 and 894890. For ESI and crystallographic data in CIF or other electro

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&z.dbd;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 π 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 medium. The metal complexes show a better inhibition effect than the ligand. Metal complexes of 2-amino-benzoic acid (phenyl-pyridin-2-yl-methylene)-hydrazide are synthesized and the structures are determined by X-ray crystallography. These compounds show appreciable corrosion inhibition efficiency for mild steel in 1 M HCl.