Cobalt thermodynamic data

Based upon thermodynamic data given in Table I, oxidant strength decreases in the order NijO > Mn02 > MnOOH > CoOOH > FeOOH. Rates of reductive dissolution in natural waters and sediments appear to follow a similar trend. When the reductant flux is increased and conditions turn anoxic, manganese oxides are reduced and dissolved earlier and more quickly than iron oxides (12, 13). No comparable information is available on release of dissolved cobalt and nickel. 

Exactly the same problem arises with the recent studies of NiO solubility by Tremaine and Leblanc (25) and again the thermodynamic data on the aqueous anionic species at 300 C are likely to be more reliable than on the Ni + ion. There is good spectroscopic evidence for complex formation in chlorides of nickel (II), (26) cobalt (II) (27), and copper (II) (28) at 300°C and above. Most of the work was done at rather high Cl concentrations but qualitatively the effects of dielectric constant and concentration are as expected. A noteworthy feature (which estimation procedures will have to allow for) is the change from 6 to 4 coordination at the lower pressures (150-300 bar) and the higher Cl concentrations. This change appears to take place with only 2 or 3 Cl ions coordinated to the metal (at least in the case of Ni(II)). 

The Hill equation, often used by biochemists dealing with 1 1 equilibria, has recently been employed by Ibers and Stynes (32) to determine thermodynamic data for the sjretem 02 g) plus base-cobalt(II) protoporphyrin IX dimethyl ester in non-aqueous media. 

Incidentally, I should say that the thermodynamic data on cobalt(III) indicates that it is a hard acid, but just barely so, and one might say borderline. It is a little harder than tetrahedral carbon and alkyl halides. So hydroxide ion in that sense would be expected perhaps to be a good nucleophilic reagent, as hard acids would like hydroxide ion. 

Crystal field theory is one of several chemical bonding models and one that is applicable solely to the transition metal and lanthanide elements. The theory, which utilizes thermodynamic data obtained from absorption bands in the visible and near-infrared regions of the electromagnetic spectrum, has met with widespread applications and successful interpretations of diverse physical and chemical properties of elements of the first transition series. These elements comprise scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel and copper. The position of the first transition series in the periodic table is shown in fig. 1.1. Transition elements constitute almost forty weight per cent, or eighteen atom per cent, of the Earth (Appendix 1) and occur in most minerals in the Crust, Mantle and Core. As a result, there are many aspects of transition metal geochemistry that are amenable to interpretation by crystal field theory. 

What thermodynamic data may be used to rationalize the observations (a) Cobalt catalysts can initiate autoxidation of p-xylene but not p-toluic acid, (b) Oxidation of isobutane leads to /-butyl hydroperoxide rather than isobutyl hydroperoxide. 

Thermodynamic data for the interaction of Eu(fod>3 with the cobalt(III) complexes of /3-diketones [99]. 

The situation becomes more complicated if a given ionization reaction is studied in solvents that differ both in their EPD and EPA properties. This may be illustrated for the complex formation between Co and Cl ions. Qualitatively, stabilities of cobalt-chloro complexes usually decrease with increasing EPD strength of the solvent (25, 26). Quantitative measurements reveal, however, a number of irregularities which cannot be understood by considering the differences in solvent donicities. Accurate thermodynamic data have recently been determined for the reaction... 

Combined Kinetic and Thermodynamic Data fob Ligand Substitution Reactions in Some Cobalt(III) Complexes... 

Figure 30 shows thermodynamic data for several cobalt phosphides under various P4 partial pressures (31). Cobalt phosphide C0P3 reduces in the following three steps ... 

Whereas for the cobalt cell measurements were carried out successfully in pure water, methanol was the solvent for the nickel cell. Apparently the author experienced the same difficulties with nickel in the aqueous medium which were already described by [29HAR/BOS]. Thus, the results of this work provide no relevant information on thermodynamic data of Ni in aqueous solution. 

LAR/CER] Larson, J. W., Cerutti, P., Garber, H. K., Hepler, L. G., Electrode potentials and thermodynamic data for aqueous ions. Copper, zinc, cadmium, iron, cobalt, and nickel, J. Phys. Chem., 72, (1968), 2902-2907. Cited on pages 84, 332. 

Where both cobalt and manganese are present in solution, the coprecipitation of hausmannite and C03O4 might be expected. Sinha et al. (25) found that random substitution of cobalt for Mn " or Mn could occur in such material occurrence of Co in manganese oxide crystal-lattice positions was noted by Bums (4). Apparently there are no thermodynamic data for mixed cobalt + manganese oxides, but the behavior of the ions can probably be represented over a considerable range of solid composition by a solid—solution model based on the equilibrium between the pure end members. Thus... 

On the basis of the computed kinetic and thermodynamic data, it is very interesting to have a comparison with the recent experimental observation of the most stable intermediates. Using online IR and NMR techniques in the cobalt-catalyzed hydromethoxycarbonylation of butadiene. Tuba et al. [77] observed several key intermediates and found that (1) the aUyl complex ( 7 -C4H7)Co(CO)3 (11a) is quite stable at 100°C, and no further reactions could be detected after the formation for several hours under 75 bar of CO at 100°C in MeOH (2) the but-2-enyl complex (CH3CH=CHCH2)Co(CO)4 (12a) is very unstable, and can be easily converted to the acyl complex (CH3CH=CHCH2CO)Co(CO)4 with CO... 

Based on thermodynamic data, the partial pressure of sulphur dioxide in the roaster bed and the bed gas temperature range have been selected to maximize production of soluble copper and cobalt and minimize production of soluble iron. 

Chromium(ni) continues to be the second most widely studied metal ion after cobalt(m). The question of dissociative (/a) or associative (/a) mechanisms for substitutions at chromium(m) has been clarified somewhat by comparing data for the formation and dissociation of the [Cr(H20)5X] + and [Cr(NH8)5X] + ions (X = unidentate leaving anion). Recent studies indicate that an associative mechanism is important for aqua-chromium(m) complexes, but for the [Cr(NHa)6X] + ions a dissociative-interchange mechanism is favoured. A summary of kinetics and thermodynamic data for the formation and aquation of [Cr(NH3)5X] + ions is given in Table 12. 

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