A simple route to synthesise palladium(II) complexes from the reaction of N-substituted pyridine-2-thiocarboxamide ligands and PdCl(2)(PPh(3))(2) has been developed. The new complexes are very soluble in common solvents and have been fully characterised (elemental analysis, FT-IR, (1)H, (31)P, (13)C-NMR), including an X-ray diffraction analysis. The molecular structures of all the complexes were determined and reveal the presence of square planar geometry around Pd with little distortion. The complexes were tested in the Suzuki coupling of electronically deactivated aryl and heteroaryl bromides and were found to have much greater activity, without using any promoting additives or phase transfer agent under aerobic conditions. Higher reaction rates are obtained by varying R substituents on the aromatic ring of pyridine-2-thiocarboxamide. The effect of other variables on the cross-coupling reaction, such as temperature, solvent and base, is also reported.
The aim of this work is to investigate the effects of film thickness, light intensity and Ag incorporation on the photoctalytic efficacy of zinc oxide films. ZnO films with different thicknesses were prepared using an automated home-made jet nebuliser spray technique. The results show that the thickness of the film has no appreciable influence on the photocatalytic efficiency of ZnO films whereas the light intensity strongly influences the photocatalytic activity of ZnO films. It is also found that doping of Ag with ZnO causes considerable enhancement in the photocatalytic activity. The dye degradation rate constant in the case of undoped ZnO film with thickness 400 nm is 0.0263min-1, whereas for Ag doped ZnO film having the same thickness, it is 0.0530 min −1 . The reason for this enhancement in the photocatalytic efficacy of ZnO:Ag film is addressed with the help of optical band gap and the reported characteristics of Ag.
Four octahedral ruthenium(II) thiocarboxamide complexes of the general formula [RuClCO(AsPh 3 ) 2 (L)] (L = N-substituted pyridine-2-thiocarboxamide) incorporating carbonyl and triphenylarsine have been synthesized from the reaction of 1 equiv of ruthenium precursor [RuHClCO-(AsPh 3 ) 3 ] with 1 equiv of thiocarboxamide ligands in refluxing ethanol in the presence of base. All the new complexes have been fully characterized by means of elemental analysis, IR, UV−vis, and NMR spectral methods. Molecular structures of all the complexes were determined by X-ray crystallography, which confirm the coordination mode of thiocarboxamide and reveal the presence of a distorted octahedral geometry around the Ru ion. All the ruthenium(II) thiocarboxamide complexes were generated as highly efficient catalysts for synthesis of secondary or tertiary amides by coupling of amines and alcohols with low catalyst loading, and the maximum yield was obtained up to 97%. The coupling reaction can be readily carried out under mild aerobic conditions, and release of water is the only byproduct. Further, the effect of substituents of the ligand, solvents, reaction temperature, time, and catalyst loading on the catalytic activity of the complexes has been investigated. A plausible mechanism is proposed for the synthesis of amides via hemiaminal as intermediate through an oxidation of an alcohol to aldehyde.
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