Polynuclear ampyrone based 3d coordination clusters

Abstract

The use of a monoanionic Schiff base ligand in transition (Co, Ni and Cu) coordination chemistry yields mono-, tetra- and pentanuclear coordination clusters with different structural motifs.

Unprecedented formation of a μ‐oxobridged dimeric copper (II) complex: Evaluation of structural, spectroscopic, and electronic properties by using theoretical studies and investigations biological activity studies of new Schiff bases derived from pyrazolone

“…π* transfer of the azomethine group (C=N). [31,47,48] As observed on the electron absorption spectrum of the Cu (II) complex, all the bands appear due to MLCT transitions at higher wavelengths indicating the coordination of the Cu ion to azomethine (C=N), as well as the broad shoulder in the 603-nm region corresponding to d ! d transmissions of the copper complex showing a very little energy due to Jahn-Teller distortion.…”

“…In the electron absorption spectrum of the ligand, the absorption band at 228‐ and 258‐nm regions show the π → π* transfer of the aromatic ring; the lower‐energy absorption band at 278, 291 regions could be assigned to π → π* transitions for the azomethine group (C=N), and the absorption band in the 356–378 region displays the n → π* transfer of the azomethine group (C=N). [ 31,47,48 ] As observed on the electron absorption spectrum of the Cu (II) complex, all the bands appear due to MLCT transitions at higher wavelengths indicating the coordination of the Cu ion to azomethine (C=N), as well as the broad shoulder in the 603‐nm region corresponding to d → d transmissions of the copper complex showing a very little energy due to Jahn–Teller distortion. [ 50–53 ]…”

“…This observation is supported by the lack of a broad band at around 3280 cm −1 , due to phenolic OH, in the complex spectra. [ 31,46,47 ] As well as the peak at 545 cm −1 attributed to the coordination of the oxygen of the phenolic group to the copper ion. [ 47–50,52 ]…”

“…The structure of the ligand approves well with the suggested structure as reported previously. [31] Yellow crystals. Yield: 82%.…”

“…In the ligand FT-IR spectrum, two prominent peaks at bands 1652 and 1591 cm À1 are represented, respectively, indicating the stretching frequency ν(C=O) and ν(C=N), respectively. [31,[46][47][48][49][50][51] Also, the same region was compared with the FT-IR spectra where the complex at 1641 and 1573 cm À1 shows ν(C=O) and ν(C=N). As can be seen, the tensile frequency of ν(C=N) shifts to the right (i.e., from 1591 cm À1 in free ligand to 1573 cm À1 in the complex, ν(C=N) it was shifted to lower wavenumber by the magnitude of 18 cm À1 ), which approves the coordination of the nitrogen of the azomethine ligand for the copper metal.…”