In Which Ni Research Articles

Role of ionic strength in the kinetics of formation of the monochelate of nickel(II) with heptane‐3,5‐dione

AbstractThe kinetics and mechanism of the reaction of Ni(II) with heptane‐,5‐dione (Hhptd) have been investigated in concentrated sodium perchlorate aqueous solutions at 298 K. The kinetic data in the different media are consistent with a mechanism in which Ni(II) reacts with the enol form of the ligand. The observed positive salt effect on the rate of the reaction of formation of the complex Nihptd+ is rationalized taking into account the increase of the rate of water exchange from the first solvation sphere of the metal ion to the bulk solvent when increasing salt concentration.

Synthetic and Spectroscopic Studies of Xanthato-Bridged Heterobimetallic Complexes Containing Diamagnetic and Paramagnetic Metal Ions

Abstract A series of heterobimetallic complexes of the form M[M′(Etxant)3] and M[M′(Etxant)3]2 have been prepared by the reaction of K[M′(Etxant)3] [M′=Ni(II), Cd(II), or Pb(II)] and metal nitrate or sulfate [Ma=Co(II), Ni(II), Cd(II), Tl(I), Pb(II), or Ag(I), Etxant=ethylxanthate]. These complexes have been characterized by elemental analysis, molecular weight, molar conductance, magnetic susceptibility, (1H, 13C) NMR, electronic, and infrared spectral studies. Magnetic moment and electronic spectral data indicate square planar geometry around Co(II) or Ni(II), except Tl[Ni(Etxant)3] in which Ni(II) is octahedrally coordinated. NMR spectra of M[M′(Etxant)3]2 clearly indicate the presence of two different ethylxanthate moieties, one attached to the diamagnetic Ni(II), Cd(II), or Pb(II) and the other to the paramagnetic Co(II) centre. Electrical conductance values indicate their nonelectrolytic behavior. Interaction of heterobimetallic complexes with different solvent have been studied and solvent characteristics (donor number, dielectric constant, EB (electrovalent) and CB (covalent) parameters) have been related to the structural properties of the complexes. On the basis of these studies, monomeric structure for M[M′(Etxant)3]2 and polymeric structure for M[M′(Etxant)3] have been suggested.

The Henryville Bed of the New Albany shale—I. Preliminary characterization of the nickel and vanadyl porphyrins in the bitumen

The nickel, vanadium, Ni(II) porphyrin and VO(II) porphyrin concentrations in the bitumen of an organic rich sample of the Henryville Bed of the New Albany shale (Mississippian-Devonian; Indiana, U.S.A.) were determined. The bitumen contains 1776 μg nickel/g and 1550 μg vanadium/g bitumen. The porphyrin concentrations of 9900 μg/g and 9100 μg/g, respectively, are higher than those reported in most source rock bitumens or crude oils. The similar abundances of Ni(II) and VO(II) porphyrins indicates a depositional environment for this sample that is transitional between strongly anoxic (VO(II) porphyrins dominant) and less anoxic in which Ni(II) porphyrins dominate. The Ni(II) and VO(II) porphyrins in the bitumen occur as etioporphyrin (etio), deoxophylloerythroetioporphyrin (DPEP), and tetrahydrobenzo-DPEP (THBD) species in the order of abundance: etio>DPEP>THBD for Ni(II) and DPEP>etio>THBD for VO(II) porphyrins. The DPEP/etio ratios of 1.4 for the VO(II) series and 0.91 for the Ni(II) series and a Vitrinite reflectance of 0.5–0.6% are consistent with the organic matter in the New Albany shale being of intermediate maturity. The carbon-number distributions of the etio, DPEP, and THBD porphyrins of the two metals are very similar. This similarity and the fact that carbon numbers of both Ni(II) and VO(II) porphyrins extend at least to C 36 suggests that the Ni(II) and VO(II) porphyrins have originated via similar geochemical pathways in the New Albany shale. The major pathway appears to be release of the porphyrins during kerogen catagenesis.

Jack bean urease: the first nickel enzyme

The article defines the development of our present understanding of the urease molecule. It describes physical and chemical properties of the enzyme, the interaction of inhibitors with the active site Ni(II) ion(s), substrate specificity and differential effects of pH on catalytic efficiency. A mechanism consistent with these data is presented. In addition, a simple model is described in which Ni(II) ion promotes nucleophilic attack of ethanol and water on a urea.

The Crystal Structure of Bis(pyridine-2-carboxamido)nickel(II) Dihydrate

Abstract The orange-red, diamagnetic crystals of [Ni(pia)2]·2H2O (piaH: pyridine-2-carboxamide) have been subjected to X-ray crystallographic analysis. They are orthorhombic, space group Pm21b-C2v2, with two formula units in a cell of dimensions: a=7.61, b=20.19 and c=4.46 Å. The crystals consist of planar molecules in which Ni(II) exhibits a square planar coordination and the two ligands are coordinated to the central nickel atom with four nitrogen atoms in trans-configuration. The molecules are tilted about 40° with respect to the plane (001), and are piled up above one another along the c-axis to form columns. These columns are linked with each other by intermolecular hydrogen bonds of N–H···O type, thus forming layers parallel to the plane (010). The layers are piled up along the b-axis by way of two water molecules which are hydrogen-bonded to the oxygen atoms of the amide groups. There exist stacking faults along this direction.