Chromium, Molybdenum and Ruthenium Complexes of 2-Hydroxyacetophenone Schiff Bases

Unsymmetrical Schiff Base Functionalized as Monobasic Tridentate Ligand on Complexation with Some Transition Metal Ions

“…Coordination of the Schiff base to the metal ions through the nitrogen atom is expected to reduce electron density in the azomethine link and lower the ν C=N absorption frequency due to the π-back bonding. The band due to ν C=N is shifted to lower frequencies and appears around 1610-1625 cm -1 , indicating coordination of the azomethine nitrogen to metal ions 17 .The weak to medium bands in the two ranges 580-615 and 430-560 cm -1 , which could be assigned to the stretching frequencies of the ν(M-O) and ν(M-N) bands, respectively, supporting that the bonding of the ligand to metal ions is achieved by the phenolic oxygen and azomethine nitrogen atom of the ligand 18 . The N-H stretching frequency at 3135-2900 cm -1 in the free ligand (having pyrrole ring) showed considerable shift in all the complexes, indicating participation of this N-H group in complexes 19 .…”

Synthesis, Characterization and Antimicrobial Activities of Copper, Nickel, Cobalt, Chromium Complexes Derived from (Z)-4-Fluoro-N-(2,7-dimethylhept-6-enylidene) benzenamine

“…10,11 The complexation leads to reduction in the double bond character of the C=N as a result of coordination between nitrogen and central metal atom. 12,13 The presence of band at 627-635 cm -1 may be assigned specifically to the O atom of water coordinated to metal.…”

Synthesis, Characterization and Theoretical Evaluation of the Transition Metal Complexes of 2, 6-Diacetylpyridine −Derived N5-Acyclic Ligands

“…The medium doublet band in the region 3389-3325 cm -1 are assigned to -NH 2 group (9) . The strong absorption bands at 1637 cm -1 and 1589-1541 cm-1 are assigned to azomethine groups of C=N (terminal) and C=N of pyridine ring respectively (8) . These bands are shifted to lower wave number in the spectra of complexes (1620-1631cm -1 ), which confirm the coordination of nitrogen atoms of C =N and nitrogen pyridine ring to metal ion via formation of six-membered ring , that is kinetically stable (3) .…”

“…B-General procedure for preparation of complexes: The preparation of complexes was carried according to the method puplished in literature (8) (20 ml) methanol was added to(2g, 0.01mol) of ligand dissolved in methanolic potassium hydroxide to keep the pH of the solution for ≈8. The resulting mixture was refluxed under nitrogen atmosphere for 3 hrs until the green in solution became, then after cooling to room temperature green precipitate formed, filtered off, washed several times with 15ml of diethyl ether ,and dried under vacuum to offered (1.31 g, 65%) yield ,scheme(2).…”