Two bench stable palladium(II) complexes [k2-(PyCH=N(CHPh2)PdCl2)] (1) and [k3-(PyCH=N(CH(Ph2)(C6H4))PdCl)] (2) supported by iminopyridine ligands (PyCH=NR) [R = CHPh2, (L1) and R = CPh3, (L2)] were synthesized and utilized as the competent catalysts in the formation of C-C coupling products for Suzuki-Miyaura and Heck-Mizoroki reactions. The palladium complex 1 was obtained by the k2 coordination of the ligand L1 to the palladium precursor whereas complex 2 was achieved by ortho-metallation of one of the phenyl groups present in ligand L2 with the Pd metal under reaction conditions making the ligand k3-ligation to the metal. Complex 2 exhibited excellent catalytic efficiency at very low catalyst loading (0.5 mol%). The new C-C bond formations of the desired products were obtained in high yield at mild reaction conditions. Wide varieties of substrate scopes were explored for the C-C bond cross-coupling reactions.
Two water soluble Zn(II) Schiff base complexes of composition [Zn(L1)3][Zn(N3)4] (1) and
[Zn(L2)2][Zn(N3)4] (2) were synthesized using bidentate N,N-donor (L1) and tridentate N,N,S-donor
(L2) of Schiff base ligands viz. (E)-1-phenyl-N-(pyridin-2-ylmethylene)methanamine (L1) and
(E)-2-((pyridin-2-ylmethylene)amino)benzenethiol (L2). Different spectroscopic tools such as FT-IR,
UV-Vis, 1H NMR and fluorescence spectroscopy have been employed to characterize complexes 1
and 2. Efforts for getting single crystals suitable for X-ray crystal structure could not be achieved.
However, from the spectroscopic data and on the basis of the structures of the related zinc(II) complexes
reported earlier in the literature, the complexes could be proposed to adopt six coordinated octahedral
geometries in one zinc centre coordinated to the ligands and while the other zinc centre has four azides
(N3) terminally coordinated resulting in the octahedral and tetrahedral metal geometries around zinc
metal atoms. The compounds behave as electrolytes in acetonitrile solution. In vitro antimicrobial
activity of the Zn(II) complexes were studied against some microbes like Aspergillus niger, Fusarium
ventricossum and Fusarium chlamydosporum. Effective antifungal activity of complex 2 was found
against the tested fungal strains.
A series of four neutral zinc complexes with substituted N,N-donor ligands viz. Ln =
(E)-N-(pyridin-2-ylmethylene)anilines of composition [Zn(NO3)2(L1)] (1), [Zn(NO3)2L2] (2),
[Zn(NO3)2L3] (3), [Zn(NO3)2L4] (4) were synthesized and characterized. The spectroscopic properties of the Zn(II) complexes were studied by UV-visible, fluorescence, IR and 1H NMR spectral analysis. All the zinc(II) complexes are water soluble and non-electrolyte in solution. Efforts for getting single crystals suitable for X-ray crystal structure could not be achieved. However, on the basis of spectral studies, compounds 1-4 are proposed to have octahedral geometry. The emission spectra of all the complexes show π-π* (intra-ligand) transition.
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