Cationic interactions cobalt

C. O. Kowenje, Spectroscopic characterization of the metal cation siting and the adsorbate-cation interactions in copper(II) and cobalt(II) exchanged Faujasite-X Zeolite, PhD thesis SUNY Binghamton USA, 2006, available at www.il.proreauest.com (UMI number 3220349). 

Martin, C.J. and Evans, W.j. (1 987) Phytic acid divalent cation interactions. V.Titrimetric, calorimetric, and binding studies with cobalt (II) and nickel (II) and their comparison with other metal ions. Journal of Inorganic Biochemistry 30, 101-119. 

LCo(H20)6] ion, and bidentate /V-donor ligands such as cn, bipy and phen form octahedral cationic complexes [Co(L-L)3] , which are much more stable to oxidation than is the hexaammine [Co(NH3)6l . Acac yields the orange [Co(acac)2(H20)2] which has the tram octahedral structure and can be dehydrated to [Co(acac)2l which attains octahedral coordination by forming the tetrameric species shown in Fig. 26.3. This is comparable with the trimeric [Ni(acac>2]3 (p. 1157), like which it shows evidence of weak ferromagnetic interactions at very low temperatures. fCo(edta)(H20)] is ostensibly analogous to the 7-coordinate Mn and complexes with the same stoichiometry, but in fact the cobalt is only 6-coordinate, 1 of the oxygen atoms of the cdta being too far away from the cobalt (272 compared to 223 pm for the other edta donor atoms) to be considered as coordinated. 

The presence of 0.3 wt.% Pd on Co-HFER (3 wt.%) catalyst results on a very important increase of low-temperature interaction of CH4 with N02, as a consequence of both the presence Pd species (Pd2+ and PdO) and the cobalt oxides redistribution (formation of Co oxo-cations and decrease of cobalt oxide). With bimetallic catalyst, under oxygen excess conditions, an increase of 30 % in the NOx conversion to N2 is attained. 

Cobalt(lll).—Complexes. Ammine complexes. Optical activity can be induced in the complexes [Co(NH3) ] and [Cofenlj] by means of outer-sphere association with chiral anions, e.g. (- - )-tartrate. Circular dichroism is observed in the d-d bands of the cations and it is suggested that this is due to (a) direct interaction between the chiral anion and the metal f/-orbitals and (b) the preferred conformation adopted by the inner-sphere ligands in the presence of a helical outer-sphere ligand. 

The oxidation of propene to acrolein has been one of the most studied selective oxidation reaction. The catalysts used are usually pure bismuth molybdates owing to the fact that these phases are present in industrial catalysts and that they exhibit rather good catalytic properties (1). However the industrial catalysts also contain bivalent cation molybdates like cobalt, iron and nickel molybdates, the presence of which improves both the activity and the selectivity of the catdysts (2,3). This improvement of performances for a mixture of phases with respect to each phase component, designated synergy effect, has recently been attributed to a support effect of the bivalent cation molybdate on the bismuth molybdate (4) or to a synergy effect due to remote control (5) or to more or less strong interaction between phases (6). However, this was proposed only in view of kinetic data obtained on a prepared supported catalyst. 

High concentration, however, is not the only means to obtain LC phases of DNA in aqueous solutions. DNA has been found to collapse upon adding in the solutions various condensing agents, which introduce effective attractive interhelical interactions. This is what happens with alcohols and other solvents, which reduce DNA solubility [40], or with multivalent cations like spermidine, spermine, and cobalt hexamine, which are thought to establish correlated counterion fluctuations with... 

Similar to the situation for quadrupole-induced relaxation, the quadrupole splitting in liquid crystals is zero if the molecular symmetry is tetrahedral or higher. Electric field gradients are zero for such symmetries so there can be no quadrupolar interaction. However, one expects to see small splittings from tetrahedral or octahedral derivatives because of structural distortions. These predominately arise from specific interactions with extraneous materials such as lipophilic headgroups in surfactant systems, as seen, for instance, in both cationic and anionic octahedral cobalt(III) species [23], Much larger splittings will be expected from other structure... 

Interestingly sulphidic compounds, having a cation coordination which is similar to that of the oxides, show large differences in their sensitivity with respect to basic molecules like NH3. Whereas the desulphurization activity of cobalt sulphide catalysts is readily poisoned by ammonia, nickel sulphide maintains its activity to a significant extent. This agrees with the observed weak interaction of the adsorbent with the doubly occupied dangling bond orbital of the Ni2+ ion. 

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