MAGNETIC AND ELECTRONIC SPECTRAL STUDIES OF FOUR, FIVE AND SIX COORDINATED COMPLEXES OF SUBSTITUTED HYDRAZIDE AND HYDRAZONES WITH DIVALENT NICKEL AND COBALT METAL IONS

Metal complexes of divalent Nickel and Cobalt metal ions have been synthesized with picolinic acid hydrazide (PH) , ortho -hydroxy acetophenone picolinoyl hydrazone ( APH) and ortho-hydroxy acetophenone iso-nicotinoyl hydrazone (AIH) ligands and were isolated at both high pH and low pH. These complexes were characterized by elemental analyses and also by electronic spectral studies and magnetic measurements. Ligands PH and AIH act as tridentate, while APH is tetradentate. All form two types of complexes, depending upon pH of the reaction mixture. At high pH complexes formed are monomeric while at high pH complexes were found to be dimeric. Dimerisation is initiated by enolic oxygen which acts like a bridging ligand between two metal ions.

A proton-responsive ligand becomes a dimetal linker for multisubstrate assembly via nitrate deoxygenation

A bidentate pyrazolylpyridine ligand (HL) was installed on divalent nickel to give [(HL)2Ni(NO3)]NO3. This species is reacted with TMS2Pz to simultaneously reduce one of the nitrate anions and deprotonate one of the ligands.

Effective Adsorption of Hexavalent Chromium and Divalent Nickel Ions from Water through Polyaniline, Iron Oxide, and Their Composites

Water pollution caused by industrial wastes containing heavy metals and dyes is a major environmental problem. This study reports on the synthesis, characterization, and utilizations of Polyaniline (PANI) and its composites with Fe3O4 for the removal of hexavalent chromium Cr(VI) and divalent nickel Ni(II) ions from water. The adsorption data were fitted in Freudlich, Langmuir, Tempkin, Dubbanin–Ruddishkawich (D–R), and Elovich adsorption isotherms. The Freundlich isotherm fits more closely to the adsorption data with R2 values of 0.9472, 0.9890, and 0.9684 for adsorption of Cr(VI) on Fe3O4, PANI, and PANI/Fe3O4 composites, respectively, while for adsorption of Ni(II) these values were 0.9366, 0.9232, and 0.9307 respectively. The effects of solution pH, initial concentration, contact time, ionic strength, and adsorbent dosage on adsorption behavior were investigated. The adsorption ability of composites was compared with pristine PANI and Fe3O4 particles. Activation energy and other thermodynamic properties such as changes in enthalpy, entropy, and Gibbs free energy indicated spontaneous and exothermic adsorption.

Dichloridobis[2-(pyridin-2-yl-κN)-1H-benzimidazole-κN 3]nickel(II) monohydrate

In the title complex, [NiCl2(C12H9N3)2]·H2O, a divalent nickel atom is coordinated by two 2-(pyridin-2-yl)-1H-benzimidazole ligands in a slightly distorted octahedral environment defined by four N donors of two N,N′-chelating ligands, along with two cis-oriented anionic chloride donors. The title complex crystallized with a water molecule disordered over two positions. In the crystal, a combination of O—H...Cl, O—H.·O and N—H...Cl hydrogen bonds, together with C—H...O, C—H...Cl and C—H...π interactions, links the complex molecules and the water molecules to form a supramolecular three-dimensional framework. The title complex is isostructural with the cobalt(II) dichloride complex reported previously [Das et al. (2011). Org. Biomol. Chem. 9, 7097–7107].

Solid state mononuclear divalent nickel spin crossover complexes

As a unique 3d8 spin crossover phenomenon, diverse electron configurations provide more options and strategies for selection.

Reactive Heterobimetallic Complex Combining Divalent Ytterbium and Dimethyl Nickel Fragments

This article presented the synthesis and characterization of original heterobimetallic species combining a divalent lanthanide fragment and a divalent nickel center bridged by the bipyrimidine ligand, a redox-active ligand. X-ray crystal structures were obtained for the Ni monomer (bipym)NiMe2, 1, as well as the heterobimetallic dimer compounds, Cp*2Yb(bipym)NiMe2, 2, along with 1H solution NMR, solid-state magnetic data, and DFT calculations only for 1. The reactivity with CO was investigated on both compounds and the stoichiometric acetone formation is discussed based on kinetic and mechanistic studies. The key role of the lanthanide fragment was demonstrated by the relatively slow CO migratory insertion step, which indicated the stability of the intermediate.

Rapid Electrodeposition of Fe–Ni Alloy Foils from Chloride Baths Containing Trivalent Iron Ions

This work presents the rapid electrodeposition of Fe–Ni alloy foils from chloride baths containing trivalent iron ions at a low pH (<0.0). The effect of the concentration of Ni2+ ions on the content, surface morphology, crystal structure, and tensile property of Fe–Ni alloys is studied in detail. The results show that the co-deposition of Fe and Ni is controlled by the adsorption of divalent nickel species at low current density and the ionic diffusion at high current density. The current density of preparing smooth and flexible Fe–Ni alloy foils is increased by increasing the concentration of Ni2+ ions, consequently the deposition rate of Fe–Ni alloy foils is increased. For example, at 0.6 M Ni2+ ions, the current density can be applied at 50 A·dm−2, along with a high deposition rate of ~288 μm·h−1.