Synthesis, characterization and structure of nickel and copper compounds containing ligands derived from keto-enehydrazines and their catalytic application for aerobic oxidation of alcohols

A β-ketoiminato palladium(II) complex for palladium deposition

The ¦-ketoiminato complex [Pd(OAc)L] (3) can be synthesized by the reaction of bis(benzoylacetone)diethylenetriamine (1, = LH) with [Pd(OAc)2] (2). The structure of 3 in the solid state has been determined by single X-ray diffraction analysis. Complex 3 crystallizes as a dimer (3 2), which is formed by hydrogen bonds between NH and OOAc functionalities of two adjacent ligands. Each of the Pd atoms is complexed by one ON2 donor unit of the polydentate ligand L − and an acetate group. Pd–Pd interactions and hydrogen bond formation between a NH and the C=O acetate moiety lead to a [4 + 2] coordination at Pd. The non-coordinated part of L exists in its ¦-keto-enamine form. The thermal decomposition behavior of 3 2 was studied by TG (thermogravimetry) and TG-MS showing that 3 2 decomposes between 200 and 500°C independent of the applied atmosphere. Under oxygen PdO is produced, while under argon Pd is formed as confirmed by PXRD measurements. Complex 3 2 was applied as a spin-coating precursor (conc. 0.1 mol L−1, volume 1.5 mL, 3000 rpm, deposition time 6 min, heating rate 50 K min−1, holding time 60 min (Ar) and 120 min (air) at T = 800°C). The as-obtained samples are characterized by granulated particles of Pd/PdO on the substrate surface. EDX (energy-dispersive X-ray spectroscopy) and XPS (X-ray photoelectron spectroscopy) measurements confirmed the formation of Pd (Ar) or PdO (O2) with up to 12 mol% C impurity.

Synthesis and evaluation of the complex-forming ability of hydroxypyranones and hydroxypyridinones with Ni (II) as possible inhibitors for urease enzyme in Helicobacter pylori

The complex-forming ability of 2-methyl-3-hydroxypyran-4-one (1a), 2-ethyl-3-hydroxypyran-4-one (1b), 1,2-dimethyl-3-hydroxypyridin-4-one (4a) and 1-ethyl-2-methyl-3-hydroxypyridin-4-one (4b) with nickel(Ni(II)) were characterized by infrared, ultraviolet, proton nuclear magnetic resonance spectroscopy and melting point. The mole-ratio of nickel:ligands was analyzed by atomic-absorption-spectrometry. The partition-coefficients (K_OW) of the compounds were also determined. The binding of ligands with Ni(II) are through deprotonated hydroxyl group (-O^-, disapeared at 3259 cm^-1) and ioan-pairs of carbonyl group (=CO^., shifted from 1650 to 1510-1515 cm^-1). The characterization of complex geometry for bis-(2-methyl-3-hydroxypyranonato)Ni(II) (5a) and bis-(2-ethyl-3-hydroxypyranonato)Ni(II) (5b) predicted to be square-planer while for bis-(1,2-dimethyl-3-hydroxypyridinonato)Ni(II) (5c) and bis-(1-ethyl-2-methyl-3-hydroxypyridinonato)Ni(II) (5d) distorted to tetrahedral-geometry. Inhibitors of Helicobacter pylori urease are nickel chelators. The compounds 1a, 4a and 4b are likely suitable ligands with complex forming-ability to make complexes of 5a, 5c and 5d with nickel. The K_OW values show the compound 5c with low partition-coefficient is more suitable ligand with lower penetration from GI lumen. Future studies demand to find out the biological activity of developed compounds on H. pylori.

Aerobic oxidation at benzylic positions catalyzed by a simple Pd(OAc)2/bis-triazole system

An extremely active palladium catalyst system for the aerobic oxidation of benzyl alcohols and benzylic C–H oxidation is described.

Four-coordinate nickel(ii) and copper(ii) complex based ONO tridentate Schiff base ligands: synthesis, molecular structure, electrochemical, linear and nonlinear properties, and computational study

The properties of NLO active ternary Ni(ii)- and Cu(ii)-unsymmetrical Schiff base complexes were explored in concert with DFT calculations.