Coordination diversity of new mononucleating hydrazone in 3d metal complexes: synthesis, characterization and structural studies

Abstract

The mononucleating hydrazone ligand LH3, a condensation product of salicyloylhydrazine and (2-formylphenoxy)acetic acid, was synthesized and its coordination behavior with first row transition metal(II) ions was investigated by isolating and elucidating the structure of the complexes using elemental analysis, conductivity and magnetic susceptibility measurements, as well as IR, 1H-NMR, electronic and EPR spectral techniques. The ligand forms mononuclear metal(II) complexes of the type [CoLH(H 2O)2], [NiLH(H 2O)2], [CuLH] and [ZnLH]. The ligand field parameters, Dq, B and ? values, in the case of the cobalt and nickel complexes support not only the octahedral geometry around the metal ion, but also imply the covalent nature of the bonding in the complexes. The EPR study revealed the presence of a spin exchange interaction in the solid copper complex and the covalent nature of the bonding. The 1H-NMR study of the zinc(II) complex indicated the non-involvement of the COOH group in the coordination. The physico-chemical study supports for the presence of octahedral geometry around cobalt(II), nickel(II) and tetrahedral geometry around copper(II) and zinc(II) ions. .

Interaction of E. coli DNA with diazine-bridged late first row transition metal complexes derived from hexadentate compartmental ligands: an approach to DNA cleavage/binding studies

“…In [Ni 2 L 2 (l-Cl)Cl 2 (H 2 O) 2 ], the bands around 680, 530 and 495 nm can be attributed, in an octahedral [24,25] model, to the three spin allowed transitions, 3 A 2g ? 3 T 2g , 3 [26]. These values are more than the spin-only values of the free metal ions, indicating the absence of metal-metal interactions.…”

Synthesis, spectral characterization and biological activity studies of transition metal complexes of Schiff base ligand containing indole moiety

“…The band due the ν NH of indole ring [14,15] observed in the region 3330-3210 cm −1 in the above complexes, indicating its non-involvement in the complexation. The band appeared at 1649 cm −1 in the ligand due to ν C=O has been disappeared in all complexes except Zn(II), Cd(II) and Hg(II) complexes, confirm enolization of amide function during complexation which is evident by the appearance of a new band in the region 1602-1597 cm −1 in these complexes due to the formation of azine moiety, >C=N−N=C< further confirms the enolization of amide carbonyl function during complexation [16][17][18]. The band due to ν C=N which was observed at 1577 cm −1 in ligand has shown a negative shift of 36-26 cm −1 in of all the complexes and appeared in the region 1551-1541 cm −1 indicating the involvement of azomethine nitrogen in the complexation with metal ions [19].…”

Synthesis, Characterization, Molecular Docking, Thermal Degradation Studies and Biological Screening of N-{[2-(Pyridin-4-ylcarbonyl)hydrazinyl]carbonothioyl}furan-2-carboxamide and its Mn(II), Ni(II), Co(II), Cu(II) and Zn(II) Complexes

“…The band appeared at 1667 cm -1 in the ligand due to ν(C=O) has been disappeared in all the metal complexes, confirm enolization of thioamide function during complexation which is evident by the appearance of a new band in the region 1616-1592 cm -1 due to the formation of >C=N-N< azine moiety [13][14][15]. The new bands appeared in this region indicating the involvement of thioamide sulphur in the complexation with metal ions [16]. The appearance of new bands in the region 3475-3445 cm -1 for metal complexes, indicate the presence of coordinated or lattice water in these complexes [17].…”