Catalytic performance of tridentate versus bidentate Co(ii) complexes supported by Schiff base ligands in vinyl addition polymerization of norbornene

Abstract

A series of Co(ii) complexes supported by Schiff base ligands were designed and synthesized. A distorted tetrahedral geometry of [LCCoCl2] showed excellent catalytic activity at 25 °C (99% yield).

Thiophene-Derived Schiff Base Complexes: Synthesis, Characterization, Antimicrobial Properties, and Molecular Docking

“… 38 Typical peaks for the aromatic C=C, C–H bond stretching appeared at the expected ranges, as reported in the literature for similar complexes. 36 Notably, no bands were observed in the range of 421–418 cm –1 corresponding to the ν(M–S) stretching vibrations in the spectra of complexes, confirming that sulfur in thiophene had not participated in the complexation. 38 …”

“…The representative (C=N) imine bond stretch appeared in the range of 1634–1627 cm –1 in [M(DE)X 2 ] . 36 It was evident from the spectral data that the (C=N) imine bond shifted to higher wavenumbers (cm –1 ) in the spectra of [M(DE)X 2 ] complexes, in comparison to the free ligand ( DE ), signifying the involvement of imine nitrogen in bonding. 37 The vibration peak found in the 1432–1377 cm –1 range was assigned to the symmetrical and asymmetrical υ(C=C) stretching vibrations of the thiophene ring, which shifted to the range of 1435–1384 cm –1 for the corresponding M(II) complexes.…”

“…The FTIR spectrum of DE exhibited a strong peak at 1633 cm –1 (Figure ), characteristic of the CN functional group. , Additionally, the absorption band characteristic of the υ­(CO) bond from thiophene-2-carboxaldehyde disappeared, demonstrating that the reaction was complete and confirming that the imine ligand was successfully synthesized. The representative (CN) imine bond stretch appeared in the range of 1634–1627 cm –1 in [M­(DE)­X 2 ] . It was evident from the spectral data that the (CN) imine bond shifted to higher wavenumbers (cm –1 ) in the spectra of [M­(DE)­X 2 ] complexes, in comparison to the free ligand ( DE ), signifying the involvement of imine nitrogen in bonding .…”