Nickel univalent

The univalent anions in this series, unlike those in the nickel group, cannot be prepared satisfactorily by solvent reduction because these anions are themselves reduced slowly by solvents. 

In haemin the iron is combined thus The two hydrogen atoms of the NH-groups of its porphyrin are replaced by two principal valencies of the metal which is also united in complex combination to the two other N-atoms (as in the complex nickel compound of dimethylglyoxime according to Tschugaev). Then the resulting complex cation combines with Cl or another univalent anion to form a salt. 

Evaluated Activity and Osmotic Cbeffcients for Aqueous Solutions Iron Chloride, and the Bi-Univalent Compounds of Nickel and Cobalt" J. Phys. Chan. Ref. 

Goldberg, R. N., R. L. Nuttall and B. R. Staples, (1979). "Evaluated Activity and Osmotic Coefficients for Aqueous Solutions FeCl2 and the Bi-univalent Compounds of Nickel and Cobalt," manuscript in press, J. Phys. Chem. Ref. Data. 

Analytical data on the soluble products isolated from chloroform are in excellent agreement with the composition 1 Ni+2 1 monoalkylated ligand 1 I or Br. The magnetic moment of this methylated complex was found to be 1.89 Bohr magnetons per nickel (II). The molar conductivities of the methylated and benzylated complexes in methanol at 25° C. are 75.4 and 68.4 ohm-1, respectively. These values approximate those expected for uni-univalent electrolytes in this solvent. The formulation of these alkylated compounds as dimeric electrolytes (structure VII) does not appear to be totally consistent with their physical properties. One or both halide ions may be bound to the metal ion. These results lead to the easily understood generalization that terminal sulfur atoms alkylate more readily than bridged mercaptide groups. 

Zeolites containing 3d transition-metal ions were considered in Beran et al. (109-112). The peculiarities of the donor-acceptor interactions of these cations located within six-membered rings with a zeolite lattice were discussed in terms of atomic charges, bond orders, and orbital energies. The redox properties of the cations, the acid-base properties of zeolites, and the dependence of these characteristics on the Si/Al ratio were discussed as well. The authors noted that the forms containing univalent copper and nickel ions should possess the highest electron-donor ability and consequently the... 

Univalent nickel ions can be prepared both on the intracrystalline surface and at fully coordinated positions by heating NiUY with alkali metal vapour. The surface Ni ions are chemically very reactive but thermally unstable those at fully co-ordinated positions are thermally stable even at 400°C, and are inert to H2, NH3, and CO although they react with oxygen to form O J. 

The reaction of divalent metals, such as copper, nickel, and so on, with dioxetanes in methanol leads to clean catalytic decomposition into carbonyl fragments/ The reaction rates increase with increasing Lewis acidity of the divalent metal and indicate, therefore, typical electrophilic cleavage of the dioxetane. On the other hand, univalent rhodium and iridium complexes catalyze the decomposition of dioxetanes into carbonyl fragments via oxidative addition. 

In contrast, when Ni(CT)Cl2 or Ni(CT)Br2 is dissolved in water, it converts to a planar, diamagnetic complex which acts as a di-univalent electrolyte. Also, the nickel (II) ion in Ni(CT)2+ will not combine with NH3 when dissolved in aqueous solution 11). These observations present a number of disturbing features. The failure of H2O and NH3 to coordinate is inferred from the fact that the solution properties are typical of planar nickel(II). Both NH3 and H2O occupy positions much higher in the spectrochemical series than Cl or Br. Consequently, if either of these neutral molecules were coordinated, the nickel atom would surely exist in its paramagnetic triplet state. 

Other Univalent Metal Ions.—The reductions of cobalt(iri) complexes by univalent zinc, cadmium, and nickel ions have been studied in aqueous solutions, using pulse radiolysis techniques. Radiolysis of aqueous solutions of bivalent metal salts and cobalt(m) complexes involve reactions of the type (5)—(7). When the cobaltic complex concentrations are... 

Pseudocapacitances have also been found in the case of metals (zinc, nickel) whose univalent ions are not known normally to exist in solution. Hence, surface concentrations could be calculated, and it was found that, e.g., in the case of zinc, they are of the order of 10 mol cm . ... 

Righellato and Davies (S34) postulated in 1930 that most uni-bivalent salts must be considered as incompletely dissociated even in dilute solutions. It may be expected then that ion association will occur for many bi-univalent salts. This would seem to be particularly true of the doubly charged transition metals. Zinc chloride is one such salt which has been shown to form many complexes. The "complexing tests" described earlier in this chapter are applied to manganous chloride, cobalt chloride, nickel chloride, and cupric chloride. 

Goldberg, R.N. R.L. Nuttall, B.R. Staples, "Evaluated activity and osmotic coefficients for aqueous solutions iron chloride, and the bi-univalent compounds of nickel and cobalt", J. Phys. Chem, Ref, Data, V8, 4, PP923-1003 (1979)... 

---