Three new coordination complexes of cobalt(III), manganese(II), and copper(II) with N,N,O-donor hydrazone ligands: syntheses and structural characterizations

Abstract

Three new coordination complexes, 2{[Co (L 1 ) 2 ]ClO 4 } Á 0.5CH 3 OH (1), [Mn(L 2 ) 2 ] (2), and [Cu(HL 2 ) (L 2 )]ClO 4 Á 2H 2 O (3) have been synthesized from two tridentate N,N,O-donor hydrazone ligands HL 1 , 2-acetylpyridine-salicyloylhydrazone, and HL 2 , 2-benzoylpyridine-salicyloylhydrazone, respectively and thoroughly characterized by elemental analysis, FT-IR, UV-Vis, electrochemical, and room temperature magnetic susceptibility measurements. Structures of the complexes have been unequivocally established by single crystal X-ray diffraction technique. Structural analysis reveals that 1 consists of two chemically similar but crystallographically independent cationic [Co(L 1 ) 2 ] ? units and 2 consists of a neutral [Mn(L 2 ) 2 ] molecule while 3 consists of a cationic [Cu(HL 2 )(L 2 )] ? unit. Metal ions display distorted octahedral geometry in 1 and 2 while in 3 it shows a distorted square pyramidal geometry. Ligand conformations around the metal ions are stabilized by the presence of intra-ligand hydrogen bonding in all the complexes. Structure of 3 reveals that a perchlorate ion linked to the complex by hydrogen bonding via a water molecule.

Metal complexes of N'-(2-hydroxy-5-phenyldiazenyl) benzylideneisonicotinohydrazide: Synthesis, spectroscopic characterization and antimicrobial activity

“…14 The Co(II), Mn(II), Cu(II) complexes of 2-acetylpyridine salicyloylhydrazone and 2-benzoylpyridine salicyloylhydrazone were also synthesized and characterized. 15 Moreover, zinc(II) complexes of 2-benzoylpyridinephenylhydrazone, 2-benzoylpyridinepara-chlorophenylhydrazone and 2-benzoylpyridinepara-nitrophenylhydrazone were prepared and characterized by elemental, spectral and single-crystal X-ray diffraction analyses. 16 Much work on metal complexes of hydrazones with different functional groups has been reported.…”

Synthesis, Characterization, and Antibacterial Activity Evaluation of New Co(II),Ni(II),Cu(II) and Zn(II) Complexes with Tridentate Hydrazones

“…The stretching vibrations of azomethine group ν (C=N) are shifted to lower frequencies in all the complexes spectra by (43-6)cm -1 , which proves that nitrogen atom of azomethine group is involved in complexation (Mishra et al, 2014). Coordination of nitrogen to the metal atom reduces the electron density in the azomethine group causing a shift in the ν (C=N) band to lower frequencies (Shit et al, 2009). The ν (N-N) observed at (991-954) cm -1 in the spectra of the ligands, shifts to higher frequencies by (38-21) cm -1 in their complexes, indicates the coordination of nitrogen atom of N-N group with metal ions (Singh et al, 2013).…”

“…The ν (N-N) observed at (991-954) cm -1 in the spectra of the ligands, shifts to higher frequencies by (38-21) cm -1 in their complexes, indicates the coordination of nitrogen atom of N-N group with metal ions (Singh et al, 2013). This phenomenone is owing to the diminution of the lone pair electrons repulsion which come from the two adjacent nitrogen atoms ,by sharing the electrons out to the metal ion (Shit et al, 2009). These observations were further substantiated by the appearance of non-ligand bands at the ranges (519-450)cm -1 and (459-406) cm -1 which are tentatively assigned to ν M-O ,ν M-N respectively (El-Boraey and Aly, 2013).…”

Spin Crossover in cis Manganese(III) Quinolylsalicylaldiminates

“…Another feature of the structures is the high degree of geometric distortion around the metal centre of 1 and 2 measured by Σ 35 and Θ 36 which are more or less identical in both cases but are clearly characteristic of Mn II compounds with planar tridentate ligands as comparable distortion parameters are found in [Mn(Phimp) 2 ] ( Σ = 127.1) 31. Indeed, in [Mn(L) 2 ] (L = 2‐benzoylpyridinesalicyloylhydrazone) where the ligand forms (5,5) membered chelate rings the distortion parameter is even higher ( Σ = 185.6) 37…”