Molecular orbital study of the dithiocyanate tetraamine nickel(II) complex

The equilibrium geometry and the electronic structure of the high-spin and low-spin forms of Ni(NH₃)₄(NCS)₂ have been studied using the CNDO-UHF type of MO-LCAO-SCF method. The adiabatic potential surface was considered as a function of equatorial and axial interatomic distances in the NiN′₄N″₂ chromophore. The equilibrium geometry, taking into account these degrees of freedom, and the harmonic force constants were obtained for this complex as well as for the dissociation limit cases, namely for Ni(NH₃)₄²⁺ and Ni(NCS)₂ complexes. The electronic structure is discussed in terms of molecular orbitals, the values of Wiberg indices, charge distributions, spin densities and the energy partitioning.     

Hexaaquacobalt(II) bis(hypophosphite) and hexaaquacobalt(II)/nickel(II) bis(hypophosphite)

The title compounds, hexa­aqua­cobalt(II) bis­(hypophosphite), [Co(H₂O)₆](H₂­PO₂)₂, and hexa­aqua­cobalt(II)/nickel(II) bis(hypophosphite), [Co_0.5Ni_0.5(H₂O)₆](H₂PO₂)₂, are shown to adopt the same structure as hexa­aqua­magnesium(II) bis­(hypophosphite). The packing of the Co(Ni) and P atoms is the same as in the structure of CaF₂. The Co^II(Ni^II) atoms have a pseudo‐face‐centred cubic cell, with a = b～ 10.3 Å, and the P atoms occupy the tetrahedral cavities. The central metal cation has a slightly distorted octahedral coordination sphere. The geometry of the hypophosphite anion in the structure is very close to ideal, with point symmetry mm2. Each O atom of the hypophosphite anion is hydrogen bonded to three water mol­ecules from different cation complexes, and each H atom of the hypophosphite anion is surrounded by three water mol­ecules from further different cation complexes.     

Homogeneous isotopic exchange between nickel(II) and bis(diethyldithiocarbamato)nickel(II) complex

Isotopic exchange behaviour of bis(diethyldithio carbamate) nickel(II) complex with nickel(II) in chloroform and methanol medium was studied. The studies were carried out at different temperatures varying the concentration of both metal ion and the complex. The results show that the complex is labile in the kinetic sense. Increase in temperature increases the isotopic exchange rate. The increase in concentration also results in enhancement of the rate of reaction.     

Homogeneous isotopic exchange between nickel(II) and bis(resacetophenone oxime) nickel(II) complex

Isotopic exchange behaviour of bis(resacetophenone oxime) nickel(II) complex with nickel(II) in tri-n-butyl phosphate (TBP) and ethanol medium has been studied. The studies were carried out at different temperatures by varying the concentrations of both metal ion and the complex. Experimental observations showed that the complex is kinetically labile. Increase in temperature increases the isotopic exchange rate. Increase in concentration of either metal ion or complex results in significant increase of the reaction rate.     

Homogeneous isotope exchange between nickel(II) and bis(resacetophenone phenylhydrazone) nickel(II) complex

Isotope exchange behavior of bis-resacetophenone phenylhydrazone) nickel(II) complex with nickel(II) in tri-n-butyl phosphate and methanol medium has been studied. The studies were carried out at different temperatures varying the concentration of both metal ion and the complex. The results show that the complex is labile in the kinetic sense. Increase in temperature increases the isotope exchange rate. The increase in concentration also results in an enhancement of the rate of reaction.     

Complexes of nickel(II) and palladium(II) with thiobenzamide

Summary The electronic and vibrational spectra of Ni^II and Pd^II complexes with thiobenzamide, L, are discussed. L acts as a sulphur donor ligand. The Pd^II compounds and (NiL₄)(ClO₄)₂ are square planar. PdL₂Cl₂ has acis-structure, while PdL₂X₂ (X=Br or I) istrans; NiL₄Cl₂ istrans-octahedral. The i.r. bands due to(M.S) and(MX) have been assigned. The influence of the anions on the properties of the complexes, both in solution and in the solid state, is discussed.