Synthesis and Structural Studies on Transition Metal Complexes Derived from 4‐Hydroxy‐4‐methyl–2‐pentanone‐1H‐benzimidazol‐2‐yl‐hydrazone

Abstract

Transition metal complexes of Cr(III), Fe(III), Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) with a tridentate ligand, 4-hydroxy-4-methyl-2-pentanone-1H-benzimidazole-2yl-hydrazone (H-HPBH) derived from the condensation of 2-hydrazinobenzimidazole and diacetone alcohol was synthesized. Characterization has been done on the basis of analytical, conductance, thermal and magnetic data, infrared,1H NMR, electronic, mass and ESR spectral data. From analytical and thermal data, the stoichiometry of the complexes has been found to be 1:1 (metal: ligand). Divalent complexes have the general formula [M(HPBH)Cl(H2O)2] in octahedral geometry, [M(HPBH)Cl] in tetrahedral and square planar stereochemistries and trivalent complexes [M(HPBH)Cl2(H2O)] in octahedral disposition. Infrared spectral data suggest that the ligand HPBH behaves as a monobasic tridentate ligand with N: N: O donor sequence towards the metal ions. On the basis of the above physicochemical data, octahedral, tetrahedral and square planar geometries were assigned for the complexes. The ligand and metal complexes were screened for their physiological activities againstE. coliandS. aureus. The order of physiological activity has been found to be Cu(II) > Ni(II) > Zn(II) > Co(II) > Cr(III) > Mn(II) > Fe (III) > ligand againstE.coliand Ni(II) > Cu(II) > Zn(II) > Mn(II) > Cr(III) > Fe(III) > Co(II) > ligand againstS. aureus.

Synthesis and Characterization of New Complexes of Co+2, Ni+2 and Cu+2 with Schiff Base Ligand

“…The IR spectra of all complexes show a positive shift of υ(C=N) (exo) (7-12) and a negative shift of υ(C=N) (ring) by (8-25) cm -1 which suggest the involvement of azomethine nitrogen as well as the azothemine nitrogen ring in the coordination (Neelamma et al, 2011).…”

Biological Activities and Chelating Properties of New Benzoyl Derivatives of 2-Substituted Benzimidazoles

“…The infrared spectra of L2 and its complexes, (Fig. [13][14][15][16][17] show stretching vibrations bands at 3056-3132 cmG 1 for C-H, bands at 1651-1658 cmG 1 for C = O. There were also bands at 1525-1530 and 1280-1393 cmG 1 (Table 3).…”

“…Furthermore, the coordination chemistry of benzimidazoles and derivatives continues to attract enormous attention because of the fact that metal complexes have shown larger antimicrobial activities than the free ligands 10 and also because of their interesting spectral, magnetic and structural properties [10][11][12][13][14][15][16] . The metal complexes of 2-substituted benzimidazole derivatives have also been found to exhibit inhibitory activities against a range of human tumor cells and as anticancer agents 11,12 .…”

Five-Coordinate Zinc(II) Complex: Synthesis, Characterization, Molecular Structure, and Antibacterial Activities of Bis-[(E)-2-hydroxy-N′-{1-(4-methoxyphenyl)ethylidene}benzohydrazido]dimethylsulfoxidezinc(II) Complex

“…In coordination chemistry, the hydrazone Schiff base ligand normally presents in enol conformation in order to bind with the metal center through the nitrogen atom from imine moiety [5][6][7] and oxygen from hydroxyl group [8,9].…”